To cite package ‘vcpen’ in publications use:

  Sinnwell J, Schaid D (2022). _vcpen: Penalized Variance Components
  Analysis_. R package version 1.9,
  <https://CRAN.R-project.org/package=vcpen>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {vcpen: Penalized Variance Components Analysis},
    author = {Jason Sinnwell and Daniel Schaid},
    year = {2022},
    note = {R package version 1.9},
    url = {https://CRAN.R-project.org/package=vcpen},
  }