To cite package ‘rtracklayer’ in publications use:

  M. Lawrence, R. Gentleman, V. Carey: "rtracklayer: an {R} package for
  interfacing with genome browsers". Bioinformatics 25:1841-1842.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {rtracklayer: an R package for interfacing with
                  genome browsers},
    author = {Michael Lawrence and Robert Gentleman and Vincent Carey},
    year = {2009},
    journal = {Bioinformatics},
    volume = {25},
    pages = {1841-1842},
    doi = {10.1093/bioinformatics/btp328},
    url = {http://bioinformatics.oxfordjournals.org/content/25/14/1841.abstract},
  }