To cite package ‘layer’ in publications use:

  Sciaini M, Scherer C (2025). _layer: Tilt your Maps and Turn Them
  into 'ggplot' Plots_. R package version 0.0.3.9000, ,
  <https://github.com/marcosci/layer>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {layer: Tilt your Maps and Turn Them into 'ggplot' Plots},
    author = {Marco Sciaini and Cédric Scherer},
    year = {2025},
    note = {R package version 0.0.3.9000, 
},
    url = {https://github.com/marcosci/layer},
  }