To cite package ‘isbn’ in publications use:

  Uryu S (2024). _isbn: Convert, Validate and Hyphenate for ISBN_. R
  package version 0.0.0.9000, <https://github.com/uribo/isbn>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {isbn: Convert, Validate and Hyphenate for ISBN},
    author = {Shinya Uryu},
    year = {2024},
    note = {R package version 0.0.0.9000},
    url = {https://github.com/uribo/isbn},
  }