To cite the package 'primer' in publications use:

Stevens MHH (2009). A Primer of Ecology with R, 2nd printing. Springer, New York.

Corresponding BibTeX entry:

  @Book{,
    title = {A Primer of Ecology with R, 2nd printing},
    author = {M. H. H. Stevens},
    publisher = {Springer},
    address = {New York},
    year = {2009},
  }