To cite package ‘RColorBrewer’ in publications use:

  Neuwirth E (2022). _RColorBrewer: ColorBrewer Palettes_. R package
  version 1.1-3, <https://CRAN.R-project.org/package=RColorBrewer>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {RColorBrewer: ColorBrewer Palettes},
    author = {Erich Neuwirth},
    year = {2022},
    note = {R package version 1.1-3},
    url = {https://CRAN.R-project.org/package=RColorBrewer},
  }