To cite package ‘lettervalue’ in publications use:

  Sassi G (2024). _lettervalue: Computing Letter Values_. R package
  version 0.2.1, <https://github.com/gilberto-sassi/lettervalue>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {lettervalue: Computing Letter Values},
    author = {Gilberto Sassi},
    year = {2024},
    note = {R package version 0.2.1},
    url = {https://github.com/gilberto-sassi/lettervalue},
  }