To cite elevatr:

Hollister J, Shah T, Nowosad J, Robitaille A, Beck M, Johnson M (2025). elevatr: Access Elevation Data from Various APIs. doi:10.5281/zenodo.8335450, R package version 0.99.1, https://github.com/usepa/elevatr/.

Corresponding BibTeX entry:

  @Manual{,
    author = {Jeffrey Hollister and Tarak Shah and Jakub Nowosad and
      Alec L. Robitaille and Marcus W. Beck and Mike Johnson},
    title = {elevatr: Access Elevation Data from Various APIs},
    year = {2025},
    note = {R package version 0.99.1},
    doi = {10.5281/zenodo.8335450},
    url = {https://github.com/usepa/elevatr/},
  }