To cite package ‘popthemes’ in publications use:

MacKintosh J (2021). popthemes: colour palettes from some 90s pop album covers. R package version 0.0.0.9000, https://github.com/johnmackintosh/popthemes.

Corresponding BibTeX entry:

  @Manual{,
    title = {popthemes: colour palettes from some 90s pop album
      covers},
    author = {John MacKintosh},
    year = {2021},
    note = {R package version 0.0.0.9000},
    url = {https://github.com/johnmackintosh/popthemes},
  }