To cite package ‘coloratio’ in publications use:

Dray M (2021). coloratio: Assess Color Contrast Ratios for Accessibility. R package version 0.0.0.9004, https://github.com/matt-dray/coloratio.

Corresponding BibTeX entry:

  @Manual{,
    title = {coloratio: Assess Color Contrast Ratios for
      Accessibility},
    author = {Matt Dray},
    year = {2021},
    note = {R package version 0.0.0.9004},
    url = {https://github.com/matt-dray/coloratio},
  }