To cite package ‘regional’ in publications use:

  Nowosad J (2024). _regional: Intra- and Inter-Regional Similarity_. R
  package version 0.4.4, <https://github.com/nowosad/regional>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {regional: Intra- and Inter-Regional Similarity},
    author = {Jakub Nowosad},
    year = {2024},
    note = {R package version 0.4.4},
    url = {https://github.com/nowosad/regional},
  }