To cite package cartography in publications use one of these:

Giraud T, Lambert N (2016). “cartography: Create and Integrate Maps in your R Workflow.” JOSS, 1(4). doi: 10.21105/joss.00054, http://dx.doi.org/10.21105/joss.00054.

Giraud T, Lambert N (2017). “Reproducible Cartography.” In Peterson M (ed.), Advances in Cartography and GIScience. ICACI 2017. Lecture Notes in Geoinformation and Cartography., 173-183. doi: 10.1007/978-3-319-57336-6_13.

Corresponding BibTeX entries:

  @Article{,
    doi = {10.21105/joss.00054},
    url = {http://dx.doi.org/10.21105/joss.00054},
    year = {2016},
    month = {aug},
    publisher = {The Open Journal},
    volume = {1},
    number = {4},
    author = {Timothée Giraud and Nicolas Lambert},
    title = {cartography: Create and Integrate Maps in your R
      Workflow},
    journal = {JOSS},
  }

  @InProceedings{,
    booktitle = {Advances in Cartography and GIScience. ICACI 2017.
      Lecture Notes in Geoinformation and Cartography.},
    author = {Timothée Giraud and Nicolas Lambert},
    editor = {Michael Peterson},
    title = {Reproducible Cartography},
    chapter = {13},
    publisher = {Springer},
    address = {Cham, Switzerland},
    year = {2017},
    pages = {173-183},
    doi = {10.1007/978-3-319-57336-6_13},
  }