To cite the Petersen package in publications use:

Schwarz CJ (2023). The Petersen-Estimator (and many more) for Two-Sample Capture-Recapture Studies with Applications to Fisheries Management R Petersen Package.

Corresponding BibTeX entry:

  @Manual{,
    title = {The Petersen-Estimator (and many more) for Two-Sample
      Capture-Recapture Studies with Applications to Fisheries
      Management {R} {Petersen} Package},
    author = {Carl James Schwarz},
    year = {2023},
  }