To cite the lmom package use:

J. R. M. Hosking (2015). L-moments. R package, version 2.5. URL: http://CRAN.R-project.org/package=lmom.

Corresponding BibTeX entry:

  @Manual{,
    title = {L-moments},
    author = {J. R. M. Hosking},
    year = {2015},
    note = {R package, version 2.5},
    url = {http://CRAN.R-project.org/package=lmom},
  }