To cite cooccur in publications use:

Daniel M. Griffith, Joseph A. Veech, Charles J. Marsh (2016). cooccur: Probabilistic Species Co-Occurrence Analysis in R. Journal of Statistical Software, 69(2), 1-17. doi:10.18637/jss.v069.c02

Corresponding BibTeX entry:

  @Article{,
    title = {{cooccur}: Probabilistic Species Co-Occurrence Analysis in
      {R}},
    author = {Daniel M. Griffith and Joseph A. Veech and Charles J.
      Marsh},
    journal = {Journal of Statistical Software, Code Snippets},
    year = {2016},
    volume = {69},
    number = {2},
    pages = {1--17},
    doi = {10.18637/jss.v069.c02},
  }