To cite the adegenet package:

Jombart, T. (2008) adegenet: a R package for the multivariate analysis of genetic markers. Bioinformatics 24: 1403-1405. doi:10.1093/bioinformatics/btn129

Corresponding BibTeX entry:

  @Article{,
    title = {adegenet: a R package for the multivariate analysis of
      genetic markers},
    journal = {Bioinformatics},
    year = {2008},
    author = {T. Jombart},
    volume = {24},
    pages = {1403-1405},
    doi = {10.1093/bioinformatics/btn129},
  }