To cite BTLLasso in publications use:

Schauberger G, Tutz G (2019). “BTLLasso: A Common Framework and Software Package for the Inclusion and Selection of Covariates in Bradley-Terry Models.” Journal of Statistical Software, 88(9), 1–29. doi:10.18637/jss.v088.i09.

Corresponding BibTeX entry:

  @Article{,
    title = {{BTLLasso}: A Common Framework and Software Package for
      the Inclusion and Selection of Covariates in {B}radley-{T}erry
      Models},
    author = {Gunther Schauberger and Gerhard Tutz},
    journal = {Journal of Statistical Software},
    year = {2019},
    volume = {88},
    number = {9},
    pages = {1--29},
    doi = {10.18637/jss.v088.i09},
  }