@Manual{r-core,
  title =        {Writing R Extensions},
  OPTkey =       {},
  author =       {{R Development Core Team}},
  organization = {R Foundation for Statistical Computing},
  address =      {Vienna, Austria},
  OPTedition =   {},
  OPTmonth =     {},
  year =         {2008},
  OPTnote =      {},
  OPTannote =    {}
}