To cite nparcomp in publications use:

  Frank Konietschke, Marius Placzek, Frank Schaarschmidt, Ludwig A.
  Hothorn (2015). nparcomp: An R Software Package for Nonparametric
  Multiple Comparisons and Simultaneous Confidence Intervals. Journal
  of Statistical Software, 64(9), 1-17. URL
  http://www.jstatsoft.org/v64/i09/.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{nparcomp}: An {R} Software Package for Nonparametric Multiple Comparisons and Simultaneous Confidence Intervals},
    author = {Frank Konietschke and Marius Placzek and Frank Schaarschmidt and Ludwig A. Hothorn},
    journal = {Journal of Statistical Software},
    year = {2015},
    volume = {64},
    number = {9},
    pages = {1--17},
    url = {http://www.jstatsoft.org/v64/i09/},
  }