To cite trainR in publications use:

Roberto Villegas-Diaz. 2021. trainR: An Interface to the National Rail Enquiries Systems. Zenodo. http://doi.org/10.5281/zenodo.4506590

Corresponding BibTeX entry:

  @Misc{trainR_villegas-diaz,
    title = {{trainR: An Interface to the National Rail Enquiries
      Systems}},
    author = {Roberto Villegas-Diaz},
    month = {January},
    year = {2021},
    publisher = {Zenodo},
    doi = {10.5281/zenodo.4506590},
    url = {https://doi.org/10.5281/zenodo.4506590},
  }