To cite the sn package in publications use:

Azzalini, A. (2013). R package 'sn': The skew-normal and skew-t distributions (version 0.4-18). URL http://azzalini.stat.unipd.it/SN

Corresponding BibTeX entry:

  @Manual{,
    title = {{R} package \texttt{sn}: The skew-normal and skew-$t$
      distributions (version 0.4-18)},
    author = {A. Azzalini},
    address = {Universit\`a di Padova, Italia},
    year = {2013},
    url = {http://azzalini.stat.unipd.it/SN},
  }