To cite cxr use:

Garcia-Callejas D, Bartomeus I, Godoy O (2019). cxr: A toolbox for modelling species coexistence.. R package version 1.1.1.

Corresponding BibTeX entry:

  @Manual{,
    title = {{cxr}: A toolbox for modelling species coexistence.},
    author = {David Garcia-Callejas and Ignasi Bartomeus and Oscar
      Godoy},
    year = {2019},
    note = {R package version 1.1.1},
  }