To cite the kohonen package publications use:

R. Wehrens and L.M.C. Buydens, Self- and Super-organising Maps in R: the kohonen package J. Stat. Softw., 21(5), 2007

Corresponding BibTeX entry:

  @Article{,
    title = {Self- and Super-organising Maps in R: the kohonen
      package},
    author = {R. Wehrens and L.M.C. Buydens},
    year = {2007},
    journal = {J. Stat. Softw.},
    volume = {21},
    number = {5},
    url = {http://www.jstatsoft.org/v21/i05},
  }