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
  <https://doi.org/10.18637/jss.v088.i09>.

A BibTeX entry for LaTeX users is

  @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},
  }