To cite clogitL1 in publications use:

  Stephen Reid, Rob Tibshirani (2014). Regularization Paths for
  Conditional Logistic Regression: The clogitL1 Package. Journal of
  Statistical Software, 58(12), 1-23. URL
  http://www.jstatsoft.org/v58/i12/.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {Regularization Paths for Conditional Logistic Regression: The {clogitL1} Package},
    author = {Stephen Reid and Rob Tibshirani},
    journal = {Journal of Statistical Software},
    year = {2014},
    volume = {58},
    number = {12},
    pages = {1--23},
    url = {http://www.jstatsoft.org/v58/i12/},
  }