To cite package ‘donut’ in publications use:

Northrop PJ (2023). donut: Nearest Neighbour Search with Variables on a Torus. R package version 1.0.3, https://github.com/paulnorthrop/donut.

Corresponding BibTeX entry:

  @Manual{,
    title = {donut: Nearest Neighbour Search with Variables on a
      Torus},
    author = {Paul J. Northrop},
    year = {2023},
    note = {R package version 1.0.3},
    url = {https://github.com/paulnorthrop/donut},
  }