To cite prefmod in publications use:

Reinhold Hatzinger, Regina Dittrich (2012). prefmod: An R Package for Modeling Preferences Based on Paired Comparisons, Rankings, or Ratings. Journal of Statistical Software, 48(10), 1-31. URL http://www.jstatsoft.org/v48/i10/.

Corresponding BibTeX entry:

  @Article{,
    title = {{prefmod}: An {R} Package for Modeling Preferences Based
      on Paired Comparisons, Rankings, or Ratings},
    author = {Reinhold Hatzinger and Regina Dittrich},
    journal = {Journal of Statistical Software},
    year = {2012},
    volume = {48},
    number = {10},
    pages = {1--31},
    url = {http://www.jstatsoft.org/v48/i10/},
  }