To cite package ‘geographiclib’ in publications use:

  Sumner M, Karney C (2026). _geographiclib: Access to
  'GeographicLib'_. R package version 0.4.2.9002,
  <https://github.com/hypertidy/geographiclib>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {geographiclib: Access to 'GeographicLib'},
    author = {Michael Sumner and Charles Karney},
    year = {2026},
    note = {R package version 0.4.2.9002},
    url = {https://github.com/hypertidy/geographiclib},
  }