To cite elevatr:

Hollister, J.W. (2025). elevatr: Access Elevation Data from Various APIs. R package version 0.99.1. https://CRAN.R-project.org/package=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/},
  }