To cite package ‘planisphere’ in publications use:

  Lambert N (2026). _planisphere: Map Projections_. R package version
  0.1.0, <https://CRAN.R-project.org/package=planisphere>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {planisphere: Map Projections},
    author = {Nicolas Lambert},
    year = {2026},
    note = {R package version 0.1.0},
    url = {https://CRAN.R-project.org/package=planisphere},
  }