To cite package 'secrdesign' in publications use:

Efford, M. G. (2019). secrdesign: Sampling Design for Spatially Explicit Capture-Recapture. R package version 2.5.7. https://CRAN.R-project.org/package=secrdesign

Corresponding BibTeX entry:

  @Manual{,
    title = {secrdesign: Sampling Design for Spatially Explicit
      Capture-Recapture},
    author = {Murray Efford},
    year = {2019},
    note = {R package version 2.5.7},
    url = {https://CRAN.R-project.org/package=secrdesign},
  }