To cite package ‘free’ in publications use:

  Lian Y, Yang Y, Gu Y, Fan J, Zhao Y, Platt R (2024). _free: Flexible
  Regularized Estimating Equations_. R package version 1.0.2,
  <https://CRAN.R-project.org/package=free>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {free: Flexible Regularized Estimating Equations},
    author = {Yi Lian and Yi Yang and Yuwen Gu and Jun Fan and Yue Zhao and Robert W. Platt},
    year = {2024},
    note = {R package version 1.0.2},
    url = {https://CRAN.R-project.org/package=free},
  }