To cite package ‘extrafrail’ in publications use:

  Gallardo D, Bourguignon M (2026). _extrafrail: Estimation and
  Additional Tools for Alternative Shared Frailty Models_. R package
  version 1.15, <https://CRAN.R-project.org/package=extrafrail>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {extrafrail: Estimation and Additional Tools for Alternative Shared Frailty
Models},
    author = {Diego Gallardo and Marcelo Bourguignon},
    year = {2026},
    note = {R package version 1.15},
    url = {https://CRAN.R-project.org/package=extrafrail},
  }
