To cite package ‘geopt’ in publications use:

  Matos C (2026). _geopt: Tools to Access and Map Spatial Datasets of
  Portugal_. R package version 0.1.0,
  <https://CRAN.R-project.org/package=geopt>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {geopt: Tools to Access and Map Spatial Datasets of Portugal},
    author = {Carlos Matos},
    year = {2026},
    note = {R package version 0.1.0},
    url = {https://CRAN.R-project.org/package=geopt},
  }