To cite package ‘startup’ in publications use:

  Bengtsson H (2024). _startup: Friendly R Startup Configuration_. R
  package version 0.23.0, <https://CRAN.R-project.org/package=startup>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {startup: Friendly R Startup Configuration},
    author = {Henrik Bengtsson},
    year = {2024},
    note = {R package version 0.23.0},
    url = {https://CRAN.R-project.org/package=startup},
  }