To cite gtfstools in publications use:

Herszenhut D, Pereira RHM, Andrade PR, Bazzo J (2022). gtfstools: General Transit Feed Specification (GTFS) Editing and Analysing Tools. doi:10.5281/zenodo.6577028, https://doi.org/10.5281/zenodo.6577028.

Corresponding BibTeX entry:

  @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},
    month = {may},
    year = {2022},
    publisher = {Zenodo},
    version = {v1.1.0},
    doi = {10.5281/zenodo.6577028},
    url = {https://doi.org/10.5281/zenodo.6577028},
  }