To cite in publications use:

Regis K. Gallon and Jerome Fournier ,2013 ,G2Sd : Grain-size Statistics and Description of Sediment ,http://cran.r-project.org/web/packages/G2Sd/index.html ,R package version 2.0

Corresponding BibTeX entry:

  @Manual{,
    title = {G2Sd : Grain-size Statistics and Description of Sediment},
    author = {Regis K. Gallon and Jerome Fournier},
    url = {http://cran.r-project.org/web/packages/G2Sd/index.html},
    year = {2013},
  }