To cite package greekLetters in publications use:

Kévin Allan Sales Rodrigues (2023). greekLetters: routines for writing Greek letters and mathematical symbols on the RStudio and RGui. R package version 1.0.2, https://CRAN.R-project.org/package=greekLetters.

Corresponding BibTeX entry:

  @Manual{,
    title = {greekLetters: routines for writing Greek letters and
      mathematical symbols on the RStudio and RGui},
    author = {{Kévin Allan Sales Rodrigues}},
    year = {2023},
    note = {R package version 1.0.2},
    url = {https://CRAN.R-project.org/package=greekLetters},
  }