To cite package ‘checkstring’ in publications use:

  Mücke M (2026). _checkstring: Common String Format Validation_. R
  package version 0.1.0.9000,
  <https://github.com/m-muecke/checkstring>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {checkstring: Common String Format Validation},
    author = {Maximilian Mücke},
    year = {2026},
    note = {R package version 0.1.0.9000},
    url = {https://github.com/m-muecke/checkstring},
  }