To cite package ‘logistf’ in publications use:

  Heinze G, Ploner M, Jiricka L, Steiner G (2025). _logistf: Firth's
  Bias-Reduced Logistic Regression_. R package version 1.26.1,
  <https://CRAN.R-project.org/package=logistf>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {logistf: Firth's Bias-Reduced Logistic Regression},
    author = {Georg Heinze and Meinhard Ploner and Lena Jiricka and Gregor Steiner},
    year = {2025},
    note = {R package version 1.26.1},
    url = {https://CRAN.R-project.org/package=logistf},
  }