To cite package ‘frailtyMMpen’ in publications use:

  Huang X, Zhou Y (2023). _frailtyMMpen: Efficient Algorithm for
  High-Dimensional Frailty Model_. R package version 1.2.1,
  <https://CRAN.R-project.org/package=frailtyMMpen>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {frailtyMMpen: Efficient Algorithm for High-Dimensional Frailty Model},
    author = {Xifen Huang and Yunpeng Zhou},
    year = {2023},
    note = {R package version 1.2.1},
    url = {https://CRAN.R-project.org/package=frailtyMMpen},
  }