To cite package ‘rms’ in publications use:

  Harrell Jr FE (2024). _rms: Regression Modeling Strategies_. R
  package version 6.9-0, <https://CRAN.R-project.org/package=rms>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {rms: Regression Modeling Strategies},
    author = {Frank E {Harrell Jr}},
    year = {2024},
    note = {R package version 6.9-0},
    url = {https://CRAN.R-project.org/package=rms},
  }