To cite package ‘ntdr’ in publications use:

  Kliems H (2024). _ntdr: Retrieve Data from the National Transit
  Database_. R package version 0.4.0.9000, ,
  <https://github.com/vgxhc/ntdr>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {ntdr: Retrieve Data from the National Transit Database},
    author = {Harald Kliems},
    year = {2024},
    note = {R package version 0.4.0.9000, },
    url = {https://github.com/vgxhc/ntdr},
  }