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.

Corresponding BibTeX entry:

  @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},
  }