To cite the 'sn' package in publications use:

Azzalini, A. (2018). The R package 'sn': The Skew-Normal and Related Distributions such as the Skew-t (version 1.5-2). URL http://azzalini.stat.unipd.it/SN

Corresponding BibTeX entry:

  @Manual{,
    title = {The {R} package \texttt{sn}: The Skew-Normal and Related
      Distributions such as the Skew-$t$ (version 1.5-2).},
    author = {A. Azzalini},
    address = {Universit\`a di Padova, Italia},
    year = {2018},
    url = {http://azzalini.stat.unipd.it/SN},
  }