To cite BradleyTerry2 in publications use:

Heather Turner, David Firth (2012). Bradley-Terry Models in R: The BradleyTerry2 Package. Journal of Statistical Software, 48(9), 1-21. URL https://www.jstatsoft.org/v48/i09/.

Corresponding BibTeX entry:

  @Article{,
    title = {Bradley-Terry Models in {R}: The {BradleyTerry2} Package},
    author = {Heather Turner and David Firth},
    journal = {Journal of Statistical Software},
    year = {2012},
    volume = {48},
    number = {9},
    pages = {1--21},
    url = {https://www.jstatsoft.org/v48/i09/},
  }