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.

Corresponding BibTeX entry:

  @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},
  }