To cite package ‘shades’ in publications use:

  Clayden J (2026). _shades: Simple Colour Manipulation_. R package
  version 1.5.0, <https://CRAN.R-project.org/package=shades>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {shades: Simple Colour Manipulation},
    author = {Jon Clayden},
    year = {2026},
    note = {R package version 1.5.0},
    url = {https://CRAN.R-project.org/package=shades},
  }