To cite package 'PresenceAbsence' in publications use:

Freeman, Elizabeth (2007). PresenceAbsence: An R Package for Presence-Absence Model Evaluation. USDA Forest Service, Rocky Mountain Research Station, 507 25th street, Ogden, UT, USA.

Corresponding BibTeX entry:

  @Manual{,
    title = {PresenceAbsence: An R Package for Presence-Absence Model
      Evaluation},
    author = {Elizabeth Freeman},
    year = {2007},
    organization = {USDA Forest Service, Rocky Mountain Research
      Station},
    address = {507 25th street, Ogden, UT, USA},
    note = {eafreeman@fs.fed.us},
  }