BibTeX and CFF
Author: Diego Hernangómez
Description: This article presents a crosswalk between BibTeX and the Citation File Format, as implemented by the cffr package.

> Important

> Generative AI tools were used to assist in producing some of the material in this article.

## Citation

Please cite this article using this BibTeX entry:

    @article{hernangomez2022,
        title        = {{BibTeX} and {CFF}, A deterministic crosswalk between two non-equivalent citation schemas},
        author       = {Diego Hernangómez},
        year         = 2022,
        journal      = {The {cffr} package},
        volume       = {Vignettes},
        doi          = {10.21105/joss.03900},
        url          = {https://docs.ropensci.org/cffr/articles/bibtex-cff.html}
    }

## BibTeX and R

BibTeX is a widely used format for storing bibliographic references, originally designed in 1985 for document‑centric workflows. It represents citations as relatively flat records with loosely constrained fields, relying on convention rather than an explicit schema.

The Citation File Format (CFF) (Druskat et al. 2021) provides a structured and extensible alternative for representing citation metadata, particularly for software and research outputs. It supports explicit typing, nested objects, and richer semantics, including contributor roles and identifiers.

In modern research workflows, both formats frequently coexist. BibTeX remains dominant in academic publishing pipelines, while CFF is increasingly adopted by infrastructure platforms such as GitHub and Zenodo.

The cffr package (Hernangómez 2021) provides a deterministic mapping (crosswalk) between BibTeX and CFF, enabling practical interoperability. Due to fundamental differences in their data models, this mapping is not bijective and may involve structural transformations, heuristic parsing, and controlled information loss.

## Conceptual differences between BibTeX and CFF

At a conceptual level, BibTeX and CFF embody different design philosophies.

BibTeX represents bibliographic information as flat records with loosely defined fields, optimized for citation rendering in documents. Semantics are largely implicit and contextual, depending on entry types and bibliography styles.

CFF, in contrast, defines a structured schema with explicit typing, nested objects, and support for richer metadata. It is designed not only for producing citations, but also for machine‑actionable interoperability across platforms.

These conceptual differences explain why a direct one‑to‑one correspondence between BibTeX and CFF is not possible. Any crosswalk must therefore rely on explicit design decisions that balance fidelity, usability, and schema constraints.

## BibTeX Definitions

Patashnik (1988) provides the canonical description of the BibTeX format. Two key concepts are central: entries and fields.

### Entries

The original BibTeX specification defines fourteen canonical entry types, each corresponding to a class of cited work:

1. @article: An article from a journal or magazine.
2. @book: A book with an explicit publisher.
3. @booklet: A printed and bound work without a named publisher.
4. @conference: Equivalent to @inproceedings, included for Scribe compatibility.
5. @inbook: A part of a book, such as a chapter or page range.
6. @incollection: A part of a book with its own title.
7. @inproceedings: An article in conference proceedings.
8. @manual: Technical documentation.
9. @mastersthesis: A Master’s thesis.
10. @misc: A fallback type when no other entry fits.
11. @phdthesis: A PhD thesis.
12. @proceedings: The proceedings of a conference.
13. @techreport: A numbered technical report.
14. @unpublished: A work not formally published.

Other implementations, notably BibLaTeX (Kime et al. 2023), extend this set with additional entry types such as online resources, software, and datasets. In standard BibTeX, such entries must typically be represented as @misc.

In R (R Core Team 2026), the base function `bibentry()` does not implement @conference. Instead, @inproceedings is used, as both share the same conceptual definition.

### Fields

BibTeX entries consist of fields whose relevance and requirement depend on the entry type. Some fields are mandatory, others optional, and some are ignored by standard bibliography styles but may still carry useful information.

The following table summarizes the relationship between BibTeX entries and their required or optional fields, following Patashnik (1988). Required fields are marked with x, and optional fields with o.

field | @article | @book | @booklet | @inbook | @incollection | @conference, @inproceedings
--- | --- | --- | --- | --- | --- | ---
address |  | o | o | o | o | o
annote |  |  |  |  |  |
author | x | x | o | x | x | x
booktitle |  |  |  |  | x | x
chapter |  |  |  | x | o |
crossref |  |  |  |  |  |
edition |  | o |  | o | o |
editor |  | x |  | x | o | o
howpublished |  |  | o |  |  |
institution |  |  |  |  |  |
journal | x |  |  |  |  |
key |  |  |  |  |  |
month | o | o | o | o | o | o
note | o | o | o | o | o | o
number | o | o |  | o | o | o
organization |  |  |  |  |  | o
pages | o |  |  | x | o | o
publisher |  | x |  | x | x | o
school |  |  |  |  |  |
series |  | o |  | o | o | o
title | x | x | x | x | x | x
type |  |  |  | o | o |
volume | o | o |  | o | o | o
year | x | x | o | x | x | x

(a) BibTeX: required fields by entry

field | @manual | @mastersthesis, phdthesis | @misc | @proceedings | @techreport | @unpublished
--- | --- | --- | --- | --- | --- | ---
address | o | o |  | o | o |
annote |  |  |  |  |  |
author | o | x | o |  | x | x
booktitle |  |  |  |  |  |
chapter |  |  |  |  |  |
crossref |  |  |  |  |  |
edition | o |  |  |  |  |
editor |  |  |  | o |  |
howpublished |  |  | o |  |  |
institution |  |  |  |  | x |
journal |  |  |  |  |  |
key |  |  |  |  |  |
month | o | o | o | o | o | o
note | o | o | o | o | o | x
number |  |  |  | o | o |
organization | o |  |  | o |  |
pages |  |  |  |  |  |
publisher |  |  |  | o |  |
school |  | x |  |  |  |
series |  |  |  | o |  |
title | x | x | o | x | x | x
type |  | o |  |  | o |
volume |  |  |  | o |  |
year | o | x | o | x | x | o

(b) BibTeX: required fields by entry (cont.)
Table 1: BibTeX entries

Only a subset of fields is required for any given entry. Fields such as title, author, and year appear across most entry types, whereas others are optional or never mandatory. This strict coupling between entry types and fields is a defining feature of BibTeX and a key source of friction when interoperating with schema‑driven formats such as CFF.

## Citation File Format

Citation File Format (CFF) consists of plain‑text, YAML‑based files that encode human‑ and machine‑readable citation metadata for software and datasets.

Two keys play a central role in CFF reference modeling:

- `preferred-citation`: Identifies a work that should be cited instead of the software or dataset itself.
- `references`: Lists related creative works, analogous to references in a scholarly article.

Both keys expect `definition-reference` objects, as defined in the CFF schema guide. These objects support explicit typing, metadata nesting, and structured identifiers, in contrast to BibTeX’s flat field model.

The following table summarizes the valid keys for CFF `definition-reference`:

`abbreviation` | `abstract` | `authors` | `collection-doi` | `collection-title`
`collection-type` | `commit` | `conference` | `contact` | `copyright`
`data-type` | `database-provider` | `database` | `date-accessed` | `date-downloaded`
`date-published` | `date-released` | `department` | `doi` | `edition`
`editors` | `editors-series` | `end` | `entry` | `filename`
`format` | `identifiers` | `institution` | `isbn` | `issn`
`issue` | `issue-date` | `issue-title` | `journal` | `keywords`
`languages` | `license` | `license-url` | `loc-end` | `loc-start`
`location` | `medium` | `month` | `nihmsid` | `notes`
`number` | `number-volumes` | `pages` | `patent-states` | `pmcid`
`publisher` | `recipients` | `repository` | `repository-artifact` | `repository-code`
`scope` | `section` | `senders` | `start` | `status`
`term` | `thesis-type` | `title` | `translators` | `type`
`url` | `version` | `volume` | `volume-title` | `year`
`year-original` |  |  |  |

Table 2: Valid keys in CFF `definition-reference` objects

Conceptually, most of these keys correspond to BibTeX fields, with one key playing a special role: `type`. In CFF, `type` explicitly identifies the kind of referenced work, making it conceptually analogous to a BibTeX entry type rather than a field1.

## Mapping strategy

The mapping implemented in cffr follows a three‑step pipeline:

1. Parse BibTeX entries into an intermediate representation.
2. Apply deterministic mapping rules to transform entry types and fields.
3. Serialize the result into CFF (and vice versa).

Whenever possible, mappings are deterministic. However, some fields require heuristic parsing, particularly when normalizing names, dates, or page ranges. As a result, semantic round‑trip reversibility is not guaranteed, even when the conversion process itself is reproducible.

    string <- "@book{einstein1921,
        title        = {Relativity: The Special and the General Theory},
        author       = {Einstein, A.},
        year         = 1920,
        publisher    = {Henry Holt and Company},
        address      = {London, United Kingdom},
        isbn         = 9781587340925}"

    # To cff
    library(cffr)
    cff_format <- cff_read_bib_text(string)

    cff_format
    #> - type: book
    #>   title: 'Relativity: The Special and the General Theory'
    #>   authors:
    #>   - family-names: Einstein
    #>     given-names: A.
    #>   year: '1920'
    #>   publisher:
    #>     name: Henry Holt and Company
    #>     address: London, United Kingdom
    #>   isbn: '9781587340925'

    # To BibTeX with S3 method
    toBibtex(cff_format)
    #> @Book{einstein:1920,
    #>   title = {Relativity: The Special and the General Theory},
    #>   author = {A. Einstein},
    #>   year = {1920},
    #>   publisher = {Henry Holt and Company},
    #>   address = {London, United Kingdom},
    #>   isbn = {9781587340925},
    #> }

## Mapping tables

The following tables summarize the mapping rules implemented in cffr. They are intended as implementation documentation rather than as a normative specification.

Mapping types include:

- direct: preserved without modification.
- transform: renamed or structurally reorganized.
- split: one field mapped to multiple fields.
- heuristic: requires parsing or inference.
- unsupported: omitted due to lack of correspondence.
- enrichment: exists only in CFF.

These mappings are not bijective and may introduce normalization effects.

> Note

> For clarity throughout this document, bold formatting (e.g., @book, edition) is used for BibTeX entries and fields, whereas inline code formatting (e.g., `book`, `edition`) is used for CFF keys.

BibTeX entry | CFF key `type` | Mapping type | Notes
--- | --- | --- | ---
@article | `type: article` | direct | -
@book | `type: book` | direct | -
@inbook | `type: chapter` | transform | Normalized to CFF taxonomy
@incollection | `type: chapter` | transform | Same as @inbook
@manual | `type: manual` | direct | -
@misc | `type: generic` | heuristic | `generic` is used as a fallback when no more specific CFF type applies.
@phdthesis | `type: thesis` | transform | The specific thesis subtype (e.g., master’s vs PhD) may be lost when mapping from BibTeX to CFF
@techreport | `type: report` | transform | -
other | `type: generic` | heuristic | Default fallback

Table 3: BibTeX entries and CFF key `type` mapping

BibTeX field | CFF key | Mapping type | Notes
--- | --- | --- | ---
title | `title` | direct | -
author | `authors` | transform | Parsed into structured name objects
editor | `editors` | transform | Same parsing logic as authors
year | `year` | direct | -
month | `month` | heuristic | Format normalization required
journal | `journal` | direct | -
booktitle | `collection-title` | transform | Container title
volume | `volume` | direct | -
number | `issue` | transform | Naming normalization
pages | `start`/`end` | split | Parsed from page range
doi | `doi` | direct | -
url | `url` | direct | -

Table 4: Core fields

BibTeX field | CFF key | Mapping type | Notes
--- | --- | --- | ---
publisher | `publisher.name` | transform | Converted to structured object
address | `publisher.location` | transform | Combined with `publisher`
institution | `institution` | direct | Used mainly in reports/thesis
school | `institution` | transform | Thesis normalization

Table 5: Structural fields

BibTeX field | CFF key | Mapping type | Notes
--- | --- | --- | ---
pages | `start`/`end` | heuristic | Requires parsing, may fail
author | `authors` | heuristic | Name splitting is not always reliable
month | `month` | heuristic | Multiple formats possible
note | `notes` | heuristic | Free text

Table 6: Parsed fields

CFF key | BibTeX equivalent | Mapping type | Notes
--- | --- | --- | ---
`preferred-citation` | - | enrichment | CFF-specific concept
`references` | - | enrichment | Not representable
`type: software` | - | unsupported | No BibTeX equivalent
`identifiers` | partial | transform | Only DOI/URL mapped

Table 7: CFF keys with no BibTeX equivalence

## Proposed Crosswalk

The cffr package provides utilities for mapping BibTeX entries (via `bibentry()`) to CFF and back. This section describes how the crosswalk is implemented, partially informed by Haines and The Ruby Citation File Format Developers (2021)2.

The crosswalk is primarily defined for BibTeX to CFF conversion, reverse mapping is a best-effort approximation and may be lossy.

After presenting the general mapping between BibTeX entries and fields and CFF keys, the next section introduces Entry Models that refine these rules for specific BibTeX entry types.

The mapping is structured according to the transformation semantics defined below.

## Transformation Semantics

The crosswalk applies different transformation strategies:

- Direct mapping: one-to-one correspondence between a BibTeX field and a CFF key.
- Structural transformation: a single field is expanded into multiple keys, such as pages to `start` and `end`.
- Heuristic mapping: equivalence is inferred based on entry type or context.
- Lossy mapping: information is discarded due to lack of an equivalent representation.

Unless stated otherwise, mappings are lossy in at least one direction.

All mappings and examples in the following sections are instances of these transformation classes.

### Entry/Key `type` Crosswalk

For mapping general BibTeX entries to CFF key `type`, the following equivalence is proposed:

BibTeX Entry | CFF key: `type` | Notes
--- | --- | ---
@article | `article` |
@book, @inbook | `book` | @inbook is a `book` with chapter and/or pages
@booklet | `pamphlet` |
@conference | `conference-paper` |
@incollection | `generic` | Needs additional fields
@inproceedings | `conference-paper` |
@manual | `manual` |
@mastersthesis, @phdthesis | `thesis` | Identified by `thesis-type`
@misc | `generic` |
@proceedings | `proceedings` |
@techreport | `report` |
@unpublished | `unpublished` |

Table 8: Entry/Type crosswalk: From BibTeX to CFF

The previous mapping has the following specifications:

- @book, @inbook, and @incollection are closely related in BibTeX3. While @inbook and @incollection both reference parts of a @book, the former is used for citing sections, chapters, pages, or other specific parts, whereas the latter is used for citing parts with a specific title. Since CFF allows keys `type: book` and `collection-type: book`, we may utilize a combination of these fields to tag each entry type in CFF accordingly.
- @mastersthesis and @phdthesis are tagged using a combination of `type: thesis` and `thesis-type` keys.

Additionally, considering that CFF allows for a wide range of values4 for the key `type`, the following mapping is applied from CFF to BibTeX:

The reverse mapping prioritizes BibTeX compatibility and normalization over exact round-trip preservation.

CFF key `type` | BibTeX Entry | Notes
--- | --- | ---
`book` | @book, @inbook | @inbook is a `book` with `section` or `start/end` (reference to page number or range).
`conference, conference-paper` | @inproceedings |
`article, magazine-article, newspaper-article` | @article |
`manual` | @manual |
`pamphlet` | @booklet |
`proceedings` | @proceedings |
`report` | @techreport |
`thesis` | @mastersthesis, @phdthesis | Using `thesis-type`
`unpublished` | @unpublished |
`generic` | @misc, @incollection | @incollection is a `generic` with `year,publisher,collection-title`
<`any other value`> | @misc |

Table 9: Entry/Key `type` crosswalk: From CFF to BibTeX

### Fields/Key Crosswalk

There is a significant similarity between the definitions and names of certain BibTeX fields and CFF keys. While the equivalence is straightforward in some cases, there are instances where certain keys need to be processed depending on the entry type.

BibTeX Field | CFF key | Notes
--- | --- | ---
address | Several possibilities | In BibTeX it may be the address of a publisher, conference, organization, institution or school.
annote | Not clear, won’t be mapped |
author | `authors` |
booktitle | `collection-title` |
chapter | `section` |
crossref | Not clear, won’t be mapped |
edition | `edition` |
editor | `editors` |
howpublished | `medium` |
institution, school, organization | `institution` | No overlapping on BibteX requirements
journal | `journal` |
key | Not clear, won’t be mapped |
month | `month` | Fallback: information in `date-published`
note | `notes` |
number | `issue` |
pages | `start` & `end` |
publisher | `publisher` |
series | `collection-title` if no booktitle |
title | `title` |
type | Won’t be mapped | This is a special key in `CFF` resembling the BibteX entry.
volume | `volume` |
year | `year` | Fallback: information in `date-published`

Table 10: BibTeX - CFF key crosswalk

We provide more detail on some of the mappings presented in the table above:

- Some fields are not mapped because there is no clear equivalence with CFF keys (such as annote, crossref, and key). Regarding the type field, the CFF key `type` corresponds to the identifier of the work (similar to an entry in BibTeX), therefore, BibTeX type won’t be mapped. These fields are always optional in BibTeX.
- For the address field, its intended use in BibTeX varies depending on the entry type (e.g., for @inproceedings, it denotes the address of the conference, while for @mastersthesis/@phdthesis, it is the address of the school, etc.). Mapping between BibTeX and CFF becomes more complex when institutional metadata is involved. This results in varying final mappings in CFF. When mapping from CFF to BibTeX, we propose to follow the same entry-based logic, using the key `location` as a fallback value when mapping to address.
- In relation with this complexity mentioned above, institution, organization and school are mapped to `institution`.
- series is mapped to `collection-title` only on those entries that do not require booktitle. In practice, this means that `collection-title` corresponds to booktitle (for @incollection and @inproceedings), and in the other cases it corresponds to series. As a consequence, series information is lost for @incollection and @inproceedings, but in those cases it is an optional field.
- When mapping from CFF to BibTeX, we propose to use `date-published` as a fallback for extracting month and year fields.
- When pages is provided as a range separated by `--`, i.e. pages = {3–5}, it is coerced as `start: 3`, `end: 5` in CFF.

#### BibLaTeX

Additionally, there are other CFF keys that correspond to BibLaTeX fields. We propose to include these fields in the crosswalk5, even though they are not part of the core BibTeX fields definition.

BibLaTeX Field | CFF key
--- | ---
abstract | `abstract`
date | `date-published`
doi | `doi`
file | `filename`
isbn | `isbn`
issn | `issn`
issuetitle | `issue-title`
keywords | `keywords`
language | `languages` (first item only)
pagetotal | `pages`
translator | `translators`
url | `url`
urldate | `date-accessed`
version | `version`

Table 11: BibLaTeX - CFF Field/Key crosswalk

## Limitations

The proposed crosswalk is subject to several structural limitations arising from differences between BibTeX and CFF schemas:

- Lossy mappings: Some BibTeX fields (e.g., crossref, annote, key) have no equivalent in CFF and are omitted during conversion.
- Ambiguous semantics: Certain fields (e.g., address, series) have context-dependent meanings in BibTeX, requiring heuristic mapping to CFF keys such as `institution`, `location`, or `collection-title`.
- Type collapsing: Multiple BibTeX entry types (e.g., @misc, @incollection) are mapped to a single CFF type (`generic`), which acts as a fallback when no more specific type is available.
- Structural transformations: Some fields require transformation rather than direct mapping (e.g., pages → `start`/`end`), altering the representation of the original data.
- Non-reversibility: Due to the above factors, round-trip conversion (BibTeX → CFF → BibTeX) is not guaranteed to preserve the original structure or semantics.

These limitations reflect fundamental differences between the two formats rather than implementation-specific constraints.

## Design decisions

The mapping implemented in cffr is guided by the following principles:

- Prefer deterministic mappings whenever possible
- Use heuristics only when unavoidable
- Normalize metadata to align with CFF conventions
- Prioritize interoperability over exact round‑trip fidelity

## Entry Models

This section documents entry‑specific mapping behavior, expanding the general crosswalk into concrete and testable models. Examples are adapted from the xampl.bib distributed with BibTeX (Patashnik and Berry 2010).

### @article

The crosswalk of @article does not require any special treatment.

BibTeX | CFF | Notes
--- | --- | ---
@article | `type: article, magazine-article, newspaper-article` |
author (required) | `authors` |
title (required) | `title` |
journal (required) | `journal` |
year (required) | `year` |
volume | `volume` |
number | `issue` |
pages | `start` and `end` |
month | `month` |
note | `notes` |

Table 12: @article Model

Round-trip

    bib <- "@article{article-full,
        title        = {The Gnats and Gnus Document Preparation System},
        author       = {Leslie A. Aamport},
        year         = 1986,
        month        = jul,
        journal      = {{G-Animal's} Journal},
        volume       = 41,
        number       = 7,
        pages        = {73+},
        note         = {This is a full ARTICLE entry}}"

    cff_read_bib_text(bib)
    #> - type: article
    #>   title: The Gnats and Gnus Document Preparation System
    #>   authors:
    #>   - family-names: Aamport
    #>     given-names: Leslie A.
    #>   year: '1986'
    #>   month: '7'
    #>   journal: G-Animal's Journal
    #>   volume: '41'
    #>   issue: '7'
    #>   notes: This is a full ARTICLE entry
    #>   start: 73+

    toBibtex(cff_read_bib_text(bib))
    #> @Article{aamport:1986,
    #>   title = {The Gnats and Gnus Document Preparation System},
    #>   author = {Leslie A. Aamport},
    #>   year = {1986},
    #>   month = {jul},
    #>   journal = {G-Animal's Journal},
    #>   volume = {41},
    #>   number = {7},
    #>   pages = {73+},
    #>   note = {This is a full ARTICLE entry},
    #> }

### @book / @inbook

In terms of the fields required in BibTeX, the primary difference between @book and @inbook is that @inbook requires a chapter or page field, while @book does not even allow these fields as optional. Therefore, we propose that an @inbook entry in CFF be treated as a @book with the following supplementary fields:

1. `section`: To denote the specific chapter within the book.
2. `start`/`end`: To indicate the range of pages covered by the section.

Additionally, note that in CFF, the series field corresponds to `collection-title`, and the address field represents the `publisher`’s `address`. Finally, the key `collection-type` is populated with `book-series`.

BibTeX | CFF | Notes
--- | --- | ---
@book, @inbook | `type: book` | If `section` or `start-end` informed, it would be treated as @inbook
author (required) | `authors` | At least one of author,editor required
editor (required) | `editors` | At least one of author,editor required
title (required) | `title` |
publisher (required) | `publisher` |
year (required) | `year` |
chapter (required in @inbook only) | `section` | Not even optional in @book
pages (required in @inbook only) | `start` and `end` | Not even optional in @book
volume | `volume` |
number | `issue` |
series | `collection-title` |
address | `address` property of `publisher` |
edition | `edition` |
month | `month` |
note | `notes` |
type | Ignored | Only optional in @inbook

Table 13: @book / @inbook Model

There are notable differences in how BibTeX and BibLaTeX handle the @inbook entry (further discussed in the Appendix A). We propose to treat a BibLaTeX @inbook as a BibTeX @incollection.

Round-trip: @book

    bib <- "@book{book-full,
        title        = {Seminumerical Algorithms},
        author       = {Donald E. Knuth},
        year         = 1981,
        month        = 10,
        publisher    = {Addison-Wesley},
        address      = {Reading, Massachusetts},
        series       = {The Art of Computer Programming},
        volume       = 2,
        note         = {This is a full BOOK entry},
        edition      = {Second}
    }"

    cff_read_bib_text(bib)
    #> - type: book
    #>   title: Seminumerical Algorithms
    #>   authors:
    #>   - family-names: Knuth
    #>     given-names: Donald E.
    #>   year: '1981'
    #>   month: '10'
    #>   publisher:
    #>     name: Addison-Wesley
    #>     address: Reading, Massachusetts
    #>   collection-title: The Art of Computer Programming
    #>   collection-type: book
    #>   volume: '2'
    #>   notes: This is a full BOOK entry
    #>   edition: Second

    toBibtex(cff_read_bib_text(bib))
    #> @Book{knuth:1981,
    #>   title = {Seminumerical Algorithms},
    #>   author = {Donald E. Knuth},
    #>   year = {1981},
    #>   month = {oct},
    #>   publisher = {Addison-Wesley},
    #>   address = {Reading, Massachusetts},
    #>   series = {The Art of Computer Programming},
    #>   volume = {2},
    #>   note = {This is a full BOOK entry},
    #>   edition = {Second},
    #> }

Round-trip: @inbook

    bib <- "@inbook{inbook-full,
        title        = {Fundamental Algorithms},
        author       = {Donald E. Knuth},
        year         = 1973,
        month        = 10,
        publisher    = {Addison-Wesley},
        address      = {Reading, Massachusetts},
        series       = {The Art of Computer Programming},
        volume       = 1,
        pages        = {10--119},
        note         = {This is a full INBOOK entry},
        edition      = {Second},
        type         = {Section},
        chapter      = {1.2}
    }"

    cff_read_bib_text(bib)
    #> - type: book
    #>   title: Fundamental Algorithms
    #>   authors:
    #>   - family-names: Knuth
    #>     given-names: Donald E.
    #>   year: '1973'
    #>   month: '10'
    #>   publisher:
    #>     name: Addison-Wesley
    #>     address: Reading, Massachusetts
    #>   collection-title: The Art of Computer Programming
    #>   collection-type: book
    #>   volume: '1'
    #>   notes: This is a full INBOOK entry
    #>   edition: Second
    #>   section: '1.2'
    #>   start: '10'
    #>   end: '119'

    toBibtex(cff_read_bib_text(bib))
    #> @InBook{knuth:1973,
    #>   title = {Fundamental Algorithms},
    #>   author = {Donald E. Knuth},
    #>   year = {1973},
    #>   month = {oct},
    #>   publisher = {Addison-Wesley},
    #>   address = {Reading, Massachusetts},
    #>   series = {The Art of Computer Programming},
    #>   volume = {1},
    #>   pages = {10--119},
    #>   note = {This is a full INBOOK entry},
    #>   chapter = {1.2},
    #>   edition = {Second},
    #> }

### @booklet

In @booklet address is mapped to `location`.

BibTeX | CFF | Notes
--- | --- | ---
@booklet | `type: pamphlet` |
title (required) | `title` |
author | `authors` |
howpublished | `medium` |
address | `location` |
month | `month` |
year | `year` |
note | `notes` |

Table 14: @booklet Model

Round-trip

    bib <- "@booklet{booklet-full,
        title        = {The Programming of Computer Art},
        author       = {Jill C. Knvth},
        date         = {1988-03-14},
        month        = feb,
        address      = {Stanford, California},
        note         = {This is a full BOOKLET entry},
        howpublished = {Vernier Art Center}
    }"

    cff_read_bib_text(bib)
    #> - type: pamphlet
    #>   title: The Programming of Computer Art
    #>   authors:
    #>   - family-names: Knvth
    #>     given-names: Jill C.
    #>   date-published: '1988-03-14'
    #>   month: '2'
    #>   location:
    #>     name: Stanford, California
    #>   notes: This is a full BOOKLET entry
    #>   medium: Vernier Art Center
    #>   year: '1988'

    toBibtex(cff_read_bib_text(bib))
    #> @Booklet{knvth:1988,
    #>   title = {The Programming of Computer Art},
    #>   author = {Jill C. Knvth},
    #>   year = {1988},
    #>   month = {feb},
    #>   address = {Stanford, California},
    #>   note = {This is a full BOOKLET entry},
    #>   howpublished = {Vernier Art Center},
    #>   date = {1988-03-14},
    #> }

### @conference / @inproceedings

Note that in this case, organization is mapped to `institution`. Additionally, series is ignored because there is no clear mapping in CFF for this field.

BibTeX | CFF | Notes
--- | --- | ---
@conference / @inproceedings | `type: conference-paper, conference` |
author (required) | `authors` |
title (required) | `title` |
booktitle (required) | `collection-title` and `conference` | Additionally `collection-type` would be populated as “proceedings”
year (required) | `year` |
editor | `editors` |
volume | `volume` |
number | `issue` |
series | Ignored |
pages | `start` and `end` |
address | `address` property of `conference` |
month | `month` |
organization | `institution` |
publisher | `publisher` |
note | `notes` |

Table 15: @conference / @inproceedings Model

Round-trip

    bib <- "@inproceedings{inproceedings-full,
        title        = {On Notions of Information Transfer in {VLSI} Circuits},
        author       = {Alfred V. Oaho and Jeffrey D. Ullman and Mihalis Yannakakis},
        year         = 1983,
        month        = mar,
        booktitle    = {Proc. Fifteenth Annual ACM Symposium on the Theory of Computing},
        publisher    = {Academic Press},
        address      = {Boston},
        series       = {All ACM Conferences},
        number       = 17,
        pages        = {133--139},
        editor       = {Wizard V. Oz and Mihalis Yannakakis},
        organization = {The OX Association for Computing Machinery}
    }"

    cff_read_bib_text(bib)
    #> - type: conference-paper
    #>   title: On Notions of Information Transfer in VLSI Circuits
    #>   authors:
    #>   - family-names: Oaho
    #>     given-names: Alfred V.
    #>   - family-names: Ullman
    #>     given-names: Jeffrey D.
    #>   - family-names: Yannakakis
    #>     given-names: Mihalis
    #>   year: '1983'
    #>   month: '3'
    #>   collection-title: Proc. Fifteenth Annual ACM Symposium on the Theory of Computing
    #>   collection-type: proceedings
    #>   publisher:
    #>     name: Academic Press
    #>   issue: '17'
    #>   editors:
    #>   - family-names: Oz
    #>     given-names: Wizard V.
    #>   - family-names: Yannakakis
    #>     given-names: Mihalis
    #>   institution:
    #>     name: The OX Association for Computing Machinery
    #>   start: '133'
    #>   end: '139'
    #>   conference:
    #>     name: Proc. Fifteenth Annual ACM Symposium on the Theory of Computing
    #>     address: Boston

    toBibtex(cff_read_bib_text(bib))
    #> @InProceedings{oaho_etall:1983,
    #>   title = {On Notions of Information Transfer in VLSI Circuits},
    #>   author = {Alfred V. Oaho and Jeffrey D. Ullman and Mihalis Yannakakis},
    #>   year = {1983},
    #>   month = {mar},
    #>   booktitle = {Proc. Fifteenth Annual ACM Symposium on the Theory of Computing},
    #>   publisher = {Academic Press},
    #>   address = {Boston},
    #>   editor = {Wizard V. Oz and Mihalis Yannakakis},
    #>   number = {17},
    #>   pages = {133--139},
    #>   organization = {The OX Association for Computing Machinery},
    #> }

### @incollection

As booktitle is a required field, we propose to map that field to `collection-title` and the `type` to `generic`. Therefore, an @incollection is a `type: generic` in CFF with a `collection-title` key. The `generic` type is used as a fallback when no semantically equivalent CFF type exists.

Additionally, series and type are ignored because there is no clear mapping in CFF for this field.

BibTeX | CFF | Notes
--- | --- | ---
@incollection | `type: generic` | Including a `collection-title` value
author (required) | `authors` |
title (required) | `title` |
booktitle (required) | `collection-title` | Additionally `collection-type` would be populated as “collection”
publisher (required) | `publisher` |
year (required) | `year` |
editor | `editors` |
volume | `volume` |
number | `issue` |
series | Ignored |
type | Ignored |
chapter | `section` |
pages | `start` and `end` |
address | `address` property of `publisher` |
edition | `edition` |
month | `month` |
note | `notes` |

Table 16: @incollection Model

Round-trip

    bib <- "@incollection{incollection-full,
        title        = {Semigroups of Recurrences},
        author       = {Daniel D. Lincoll},
        year         = 1977,
        month        = sep,
        booktitle    = {High Speed Computer and Algorithm Organization},
        publisher    = {Academic Press},
        address      = {New York},
        series       = {Fast Computers},
        number       = 23,
        pages        = {179--183},
        note         = {This is a full INCOLLECTION entry},
        editor       = {David J. Lipcoll and D. H. Lawrie and A. H. Sameh},
        chapter      = 3,
        type         = {Part},
        edition      = {Third}
    }"

    cff_read_bib_text(bib)
    #> - type: generic
    #>   title: Semigroups of Recurrences
    #>   authors:
    #>   - family-names: Lincoll
    #>     given-names: Daniel D.
    #>   year: '1977'
    #>   month: '9'
    #>   collection-title: High Speed Computer and Algorithm Organization
    #>   collection-type: collection
    #>   publisher:
    #>     name: Academic Press
    #>     address: New York
    #>   issue: '23'
    #>   notes: This is a full INCOLLECTION entry
    #>   editors:
    #>   - family-names: Lipcoll
    #>     given-names: David J.
    #>   - family-names: Lawrie
    #>     given-names: D. H.
    #>   - family-names: Sameh
    #>     given-names: A. H.
    #>   section: '3'
    #>   edition: Third
    #>   start: '179'
    #>   end: '183'

    toBibtex(cff_read_bib_text(bib))
    #> @InCollection{lincoll:1977,
    #>   title = {Semigroups of Recurrences},
    #>   author = {Daniel D. Lincoll},
    #>   year = {1977},
    #>   month = {sep},
    #>   booktitle = {High Speed Computer and Algorithm Organization},
    #>   publisher = {Academic Press},
    #>   address = {New York},
    #>   editor = {David J. Lipcoll and D. H. Lawrie and A. H. Sameh},
    #>   number = {23},
    #>   pages = {179--183},
    #>   note = {This is a full INCOLLECTION entry},
    #>   chapter = {3},
    #>   edition = {Third},
    #> }

### @manual

As in the case of @conference / @inproceedings, organization is mapped to `institution`.

BibTeX | CFF | Notes
--- | --- | ---
@manual | `type: manual` |
title (required) | `title` |
author | `authors` |
organization | `institution` |
address | `address` property of `organization` | On missing `organization` mapped to `location`
edition | `edition` |
month | `month` |
year | `year` |
note | `notes` |

Table 17: @manual Model

Round-trip

Note that month cannot be coerced to a single integer in the range `1--12` as required in CFF, so it is ignored to avoid validation errors.

    bib <- "@manual{manual-full,
      title        = {The Definitive Computer Manual},
        author       = {Larry Manmaker},
        year         = 1986,
        month        = {apr-may},
        address      = {Silicon Valley},
        note         = {This is a full MANUAL entry},
        organization = {Chips-R-Us},
        edition      = {Silver}
    }"

    cff_read_bib_text(bib)
    #> - type: manual
    #>   title: The Definitive Computer Manual
    #>   authors:
    #>   - family-names: Manmaker
    #>     given-names: Larry
    #>   year: '1986'
    #>   month: '4'
    #>   notes: This is a full MANUAL entry
    #>   institution:
    #>     name: Chips-R-Us
    #>     address: Silicon Valley
    #>   edition: Silver

    toBibtex(cff_read_bib_text(bib))
    #> @Manual{manmaker:1986,
    #>   title = {The Definitive Computer Manual},
    #>   author = {Larry Manmaker},
    #>   year = {1986},
    #>   month = {apr},
    #>   address = {Silicon Valley},
    #>   note = {This is a full MANUAL entry},
    #>   edition = {Silver},
    #>   organization = {Chips-R-Us},
    #> }

### @mastersthesis / @phdthesis

In terms of fields required by BibTeX, it is identical for both @mastersthesis and @phdthesis.

We propose here to identify each type of thesis using the key `thesis-type`. If `thesis-type` contains a regex pattern `(?i)(phd)`, it is recognized as @phdthesis.

Additionally, school is mapped to `institution`.

BibTeX | CFF | Notes
--- | --- | ---
@mastersthesis, @phdthesis | `type: thesis` | Use also `thesis-type` for identifying the thesis type.
author (required) | `authors` |
title (required) | `title` |
school (required) | `institution` |
year (required) | `year` |
type | Ignored |
address | `address` property of `institution` |
month | `month` |
note | `notes` |

Table 18: @mastersthesis / @phdthesis Model

Round-trip: @mastersthesis

    bib <- "@mastersthesis{mastersthesis-full,
        title        = {Mastering Thesis Writing},
        author       = {Edouard Masterly},
        year         = 1988,
        month        = jun,
        address      = {English Department},
        note         = {This is a full MASTERSTHESIS entry},
        school       = {Stanford University},
        type         = {Master's project}
    }"

    cff_read_bib_text(bib)
    #> - type: thesis
    #>   title: Mastering Thesis Writing
    #>   authors:
    #>   - family-names: Masterly
    #>     given-names: Edouard
    #>   year: '1988'
    #>   month: '6'
    #>   notes: This is a full MASTERSTHESIS entry
    #>   institution:
    #>     name: Stanford University
    #>     address: English Department
    #>   thesis-type: Master's Thesis

    toBibtex(cff_read_bib_text(bib))
    #> @MastersThesis{masterly:1988,
    #>   title = {Mastering Thesis Writing},
    #>   author = {Edouard Masterly},
    #>   year = {1988},
    #>   month = {jun},
    #>   address = {English Department},
    #>   note = {This is a full MASTERSTHESIS entry},
    #>   school = {Stanford University},
    #> }

Round-trip: @phdthesis

    bib <- "@phdthesis{phdthesis-full,
        title        = {Fighting Fire with Fire: Festooning {F}rench Phrases},
        author       = {F. Phidias Phony-Baloney},
        year         = 1988,
        month        = jun,
        address      = {Department of French},
        note         = {This is a full PHDTHESIS entry},
        school       = {Fanstord University},
        type         = {{PhD} Dissertation}
    }"

    cff_read_bib_text(bib)
    #> - type: thesis
    #>   title: 'Fighting Fire with Fire: Festooning French Phrases'
    #>   authors:
    #>   - family-names: Phony-Baloney
    #>     given-names: F. Phidias
    #>   year: '1988'
    #>   month: '6'
    #>   notes: This is a full PHDTHESIS entry
    #>   institution:
    #>     name: Fanstord University
    #>     address: Department of French
    #>   thesis-type: PhD Thesis

    toBibtex(cff_read_bib_text(bib))
    #> @PhdThesis{phonybaloney:1988,
    #>   title = {Fighting Fire with Fire: Festooning French Phrases},
    #>   author = {F. Phidias Phony-Baloney},
    #>   year = {1988},
    #>   month = {jun},
    #>   address = {Department of French},
    #>   note = {This is a full PHDTHESIS entry},
    #>   school = {Fanstord University},
    #> }

### @misc

The crosswalk of @misc does not require any special treatment. This entry does not require any field.

Note also that it is mapped to `type: generic` as @incollection, but in this case booktitle is not even an option, so the proposed definition should cover both @misc and @incollection without problems.

BibTeX | CFF | Notes
--- | --- | ---
@misc | `type: generic` |
author | `authors` |
title | `title` |
howpublished | `medium` |
month | `month` |
year | `year` |
note | `notes` |

Table 19: @misc Model

Round-trip

    bib <- "@misc{misc-full,
        title        = {Handing out random pamphlets in airports},
        author       = {Joe-Bob Missilany},
        year         = 1984,
        month        = oct,
        note         = {This is a full MISC entry},
        howpublished = {Handed out at O'Hare}
    }"

    cff_read_bib_text(bib)
    #> - type: generic
    #>   title: Handing out random pamphlets in airports
    #>   authors:
    #>   - family-names: Missilany
    #>     given-names: Joe-Bob
    #>   year: '1984'
    #>   month: '10'
    #>   notes: This is a full MISC entry
    #>   medium: Handed out at O'Hare

    toBibtex(cff_read_bib_text(bib))
    #> @Misc{missilany:1984,
    #>   title = {Handing out random pamphlets in airports},
    #>   author = {Joe-Bob Missilany},
    #>   year = {1984},
    #>   month = {oct},
    #>   note = {This is a full MISC entry},
    #>   howpublished = {Handed out at O'Hare},
    #> }

### @proceedings

The proposed model is consistent with @conference / @inproceedings. Note that @proceedings does not prescribe an author field. In these cases, as `authors` is required in CFF, we use anonymous6 when mapping to CFF and omit it when mapping from CFF to BibTeX.

BibTeX | CFF | Notes
--- | --- | ---
@proceedings | `type: proceedings` |
title (required) | `title` and `conference` |
year (required) | `year` |
editor | `editors` |
volume | `volume` |
number | `issue` |
series | `collection-title` | Additionally `collection-type` would be populated as “proceedings”
address | `address` property of `conference` |
month | `month` |
organization | `institution` |
publisher | `publisher` |
note | `notes` |

Table 20: @proceedings Model

Round-trip

    bib <- "@proceedings{proceedings-full,
        title        = {Proc. Fifteenth Annual ACM Symposium on the Theory of Computing},
        year         = 1983,
        month        = mar,
        publisher    = {Academic Press},
        address      = {Boston},
        series       = {All ACM Conferences},
        number       = 17,
        note         = {This is a full PROCEEDINGS entry},
        editor       = {Wizard V. Oz and Mihalis Yannakakis},
        organization = {The OX Association for Computing Machinery}
    }"

    cff_read_bib_text(bib)
    #> - type: proceedings
    #>   title: Proc. Fifteenth Annual ACM Symposium on the Theory of Computing
    #>   authors:
    #>   - name: anonymous
    #>   year: '1983'
    #>   month: '3'
    #>   publisher:
    #>     name: Academic Press
    #>   collection-title: All ACM Conferences
    #>   collection-type: proceedings
    #>   issue: '17'
    #>   notes: This is a full PROCEEDINGS entry
    #>   editors:
    #>   - family-names: Oz
    #>     given-names: Wizard V.
    #>   - family-names: Yannakakis
    #>     given-names: Mihalis
    #>   institution:
    #>     name: The OX Association for Computing Machinery
    #>   conference:
    #>     name: All ACM Conferences
    #>     address: Boston

    toBibtex(cff_read_bib_text(bib))
    #> @Proceedings{oz_etall:1983,
    #>   title = {Proc. Fifteenth Annual ACM Symposium on the Theory of Computing},
    #>   year = {1983},
    #>   month = {mar},
    #>   publisher = {Academic Press},
    #>   address = {Boston},
    #>   editor = {Wizard V. Oz and Mihalis Yannakakis},
    #>   series = {All ACM Conferences},
    #>   number = {17},
    #>   note = {This is a full PROCEEDINGS entry},
    #>   organization = {The OX Association for Computing Machinery},
    #> }

### @techreport

The crosswalk of @techreport does not require any special treatment.

BibTeX | CFF | Notes
--- | --- | ---
@techreport | `type: report` |
author (required) | `authors` |
title (required) | `title` |
institution (required) | `institution` |
year (required) | `year` |
type | Ignored |
number | `issue` |
address | `address` property of `institution` |
month | `month` |
note | `notes` |

Table 21: @techreport Model

Round-trip

    bib <- "@techreport{techreport-full,
        title        = {A Sorting Algorithm},
        author       = {Tom Terrific},
        year         = 1988,
        month        = oct,
        address      = {Computer Science Department, Fanstord, California},
        number       = 7,
        note         = {This is a full TECHREPORT entry},
        institution  = {Fanstord University},
        type         = {Wishful Research Result}
    }"

    cff_read_bib_text(bib)
    #> - type: report
    #>   title: A Sorting Algorithm
    #>   authors:
    #>   - family-names: Terrific
    #>     given-names: Tom
    #>   year: '1988'
    #>   month: '10'
    #>   issue: '7'
    #>   notes: This is a full TECHREPORT entry
    #>   institution:
    #>     name: Fanstord University
    #>     address: Computer Science Department, Fanstord, California

    toBibtex(cff_read_bib_text(bib))
    #> @TechReport{terrific:1988,
    #>   title = {A Sorting Algorithm},
    #>   author = {Tom Terrific},
    #>   year = {1988},
    #>   month = {oct},
    #>   address = {Computer Science Department, Fanstord, California},
    #>   number = {7},
    #>   note = {This is a full TECHREPORT entry},
    #>   institution = {Fanstord University},
    #> }

### @unpublished

The crosswalk of @unpublished does not require any special treatment.

BibTeX | CFF | Notes
--- | --- | ---
@unpublished | `type: unpublished` |
author (required) | `authors` |
title (required) | `title` |
note (required) | `notes` |
month | `month` |
year | `year` |

Table 22: @unpublished Model

Round-trip

    bib <- "@unpublished{unpublished-minimal,
        title        = {Lower Bounds for Wishful Research Results},
        author       = {Ulrich Underwood and Ned Net and Paul Pot},
        note         = {Talk at Fanstord University (this is a minimal UNPUBLISHED entry)}
    }"

    cff_read_bib_text(bib)
    #> - type: unpublished
    #>   title: Lower Bounds for Wishful Research Results
    #>   authors:
    #>   - family-names: Underwood
    #>     given-names: Ulrich
    #>   - family-names: Net
    #>     given-names: Ned
    #>   - family-names: Pot
    #>     given-names: Paul
    #>   notes: Talk at Fanstord University (this is a minimal UNPUBLISHED entry)

    toBibtex(cff_read_bib_text(bib))
    #> @Unpublished{underwood_etall,
    #>   title = {Lower Bounds for Wishful Research Results},
    #>   author = {Ulrich Underwood and Ned Net and Paul Pot},
    #>   note = {Talk at Fanstord University (this is a minimal UNPUBLISHED entry)},
    #> }

## Conclusion

This article presents a practical and reproducible crosswalk between BibTeX and CFF.

Although the formats are not fully equivalent, the deterministic mapping implemented in cffr enables consistent transformations across heterogeneous citation ecosystems. By making design decisions explicit and documenting limitations, this work supports interoperable citation workflows bridging legacy bibliographic systems and modern software‑centric practices.

## Appendix A: @inbook in BibTeX and BibLaTeX

The definition of @inbook and @incollection in BibTeX (Patashnik 1988) is as follows:

> - @inbook: A part of a book, which may be a chapter (or section) and/or a range of pages. Required fields: author or editor, title, chapter and/or pages, publisher, year (…)

> - @incollection: A part of a book having its own title. Required fields: author, title, booktitle, publisher, year (…)

Whereas BibLaTeX (Kime et al. 2023) specifies:

> - @inbook: A part of a book which forms a self-contained unit with its own title. Note that the profile of this entry type is different from standard BibTeX, see § 2.3.1. Required fields: author, title, booktitle, year/date (…).

When considering required fields, an important difference is the booktitle requirement in BibLaTeX. Notably, BibTeX @incollection requires also this field. Moreover, both BibTeX @incollection and BibLaTeX @inbook emphasize its reference to “a part of a book (…) with its own title”.

In this document, the proposed crosswalk ensures full compatibility with BibTeX. Hence, we propose to consider a BibLaTeX @inbook entry as equivalent to a BibTeX @incollection, given the congruence in their definitions and field requirements.

Round-trip

    bib <- "@inbook{inbook-biblatex,
        author       = {Yihui Xie and Christophe Dervieux and Emily Riederer},
        title        = {Bibliographies and citations},
        booktitle    = {{R} Markdown Cookbook},
        date         = {2023-12-30},
        publisher    = {Chapman and Hall/CRC},
        address      = {Boca Raton, Florida},
        series       = {The {R} Series},
        isbn         = 9780367563837,
        url          = {https://yihui.org/rmarkdown-cookbook/},
        chapter      = {4.5}
    }"

    cff_read_bib_text(bib)
    #> - type: generic
    #>   title: Bibliographies and citations
    #>   authors:
    #>   - family-names: Xie
    #>     given-names: Yihui
    #>   - family-names: Dervieux
    #>     given-names: Christophe
    #>   - family-names: Riederer
    #>     given-names: Emily
    #>   collection-title: R Markdown Cookbook
    #>   collection-type: collection
    #>   date-published: '2023-12-30'
    #>   publisher:
    #>     name: Chapman and Hall/CRC
    #>     address: Boca Raton, Florida
    #>   isbn: '9780367563837'
    #>   url: https://yihui.org/rmarkdown-cookbook/
    #>   section: '4.5'
    #>   year: '2023'
    #>   month: '12'

    toBibtex(cff_read_bib_text(bib))
    #> @InCollection{xie_etall:2023,
    #>   title = {Bibliographies and citations},
    #>   author = {Yihui Xie and Christophe Dervieux and Emily Riederer},
    #>   year = {2023},
    #>   month = {dec},
    #>   booktitle = {R Markdown Cookbook},
    #>   publisher = {Chapman and Hall/CRC},
    #>   address = {Boca Raton, Florida},
    #>   isbn = {9780367563837},
    #>   url = {https://yihui.org/rmarkdown-cookbook/},
    #>   chapter = {4.5},
    #>   date = {2023-12-30},
    #> }

## Appendix B: CFF key: `type` values

From Druskat et al. (2019), Table 4: Complete list of CFF reference types for key `type`. Only a subset of these types is actively used in the proposed crosswalk.

Reference type string | Description
--- | ---
`art` | A work of art, e.g., a painting
`article` |
`audiovisual` |
`bill` | A legal bill
`blog` | A blog post
`book` | A book or e-book
`catalogue` |
`conference` |
`conference-paper` |
`data` | A data set
`database` | An aggregated or online database
`dictionary` |
`edited-work` | An edited work, e.g., a book
`encyclopedia` |
`film-broadcast` | A film or broadcast
`generic` | The fallback type
`government-document` |
`grant` | A research or other grant
`hearing` |
`historical-work` | A historical work, e.g., a medieval manuscript
`legal-case` |
`legal-rule` |
`magazine-article` |
`manual` | A manual
`map` | A geographical map
`multimedia` | A multimedia file
`music` | A music file or sheet music
`newspaper-article` |
`pamphlet` |
`patent` |
`personal-communication` |
`proceedings` | Conference proceedings
`report` |
`serial` |
`slides` | Slides, i.e., a published slide deck
`software` | Software
`software-code` | Software source code
`software-container` | A software container (e.g., a docker container)
`software-executable` | An executable software, i.e., a binary/artifact
`software-virtual-machine` | A virtual machine/vm image
`sound-recording` |
`standard` |
`statute` |
`thesis` | An academic thesis
`unpublished` |
`video` | A video recording
`website` |

Table 23: Complete list of CFF reference types
Druskat, Stephan, Jurriaan H. Spaaks, Neil Chue Hong, et al. 2021. Citation File Format. https://doi.org/10.5281/zenodo.5171937.
Druskat, Stephan, Jurriaan H. Spaaks, Neil Chue Hong, Robert Haines, and James Baker. 2019. Citation File Format (CFF) - Specifications. https://doi.org/10.5281/ZENODO.3515946.
Haines, Robert, and The Ruby Citation File Format Developers. 2021. Ruby CFF Library. Zenodo. https://doi.org/10.5281/ZENODO.1184077.
Hernangómez, Diego. 2021. “cffr: Generate Citation File Format Metadata for R Packages.” Journal of Open Source Software 6 (67): 3900. https://doi.org/10.21105/joss.03900.
Kime, Philip, Moritz Wemheuer, and Philipp Lehman. 2023. The biblatex Package. https://osl.ugr.es/CTAN/macros/latex/contrib/biblatex/doc/biblatex.pdf.
Patashnik, Oren. 1988. BIBTEXTING. https://osl.ugr.es/CTAN/biblio/bibtex/base/btxdoc.pdf.
Patashnik, Oren, and Karl Berry. 2010. CTAN: Package Bibtex. Version 0.99d. https://ctan.org/pkg/bibtex.
R Core Team. 2026. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing. https://doi.org/10.32614/R.manuals.
Rees, Clea F. 2017. BibLaTeX Cheat Sheet. https://osl.ugr.es/CTAN/info/biblatex-cheatsheet/biblatex-cheatsheet.pdf.

1. See a complete list of possible values of CFF `type` in Appendix B↩︎

2. Note that this software performs only the mapping from CFF to BibTeX, however cffr can perform the mapping in both directions.↩︎

3. Note that BibLaTeX (Kime et al. 2023) handles @inbook differently, see Appendix A.↩︎

4. See Appendix B for all possible values. Information extracted from Druskat et al. (2019).↩︎

5. See Rees (2017) for a preview of the accepted BibLaTeX fields.↩︎

6. As proposed on How to deal with unknown individual authors?, (Guide to Citation File Format schema version 1.2.0)↩︎