To cite package ‘gtfstools’ in publications use:

  Herszenhut D, Pereira R, Andrade P, Bazzo J (2024). _gtfstools:
  General Transit Feed Specification (GTFS) Editing and Analysing
  Tools_. R package version 1.3.0,
  <https://CRAN.R-project.org/package=gtfstools>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {gtfstools: General Transit Feed Specification (GTFS) Editing and Analysing
Tools},
    author = {Daniel Herszenhut and Rafael H. M. Pereira and Pedro R. Andrade and Joao Bazzo},
    year = {2024},
    note = {R package version 1.3.0},
    url = {https://CRAN.R-project.org/package=gtfstools},
  }