To cite the 'PDQutils' package in publications use:

Pav SE (2017). PDQutils: PDQ Functions via Gram Charlier, Edgeworth, and Cornish Fisher Approximations. R package version 0.1.6, https://github.com/shabbychef/PDQutils.

Corresponding BibTeX entry:

  @Manual{PDQutils-Manual,
    title = {{PDQutils}: {PDQ} Functions via {G}ram {C}harlier,
      {E}dgeworth, and {C}ornish {F}isher Approximations},
    author = {Steven E. Pav},
    year = {2017},
    note = {R package version 0.1.6},
    url = {https://github.com/shabbychef/PDQutils},
  }