
@article{friendly2002corrgrams,
  author =       {Michael Friendly},
  title =        {Corrgrams: Exploratory displays for correlation matrices},
  journal =      {The American Statistician},
  year =         2002,
  volume =       56,
  pages =        {316--324},
  url =          {http://www.math.yorku.ca/SCS/Papers/corrgram.pdf},
  doi={10.1198/000313002533}
}
