To cite varPro in publications use:

  Ishwaran H. and Kogalur U.B. (2026). Model-Independent Variable
  Selection via the Rule-Based Variable Priority, R package version
  3.1.0.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {Model-Independent Variable Selection via the Rule-Based Variable
Priority},
    author = {H. Ishwaran and U.B. Kogalur},
    publisher = {manual},
    year = {2026},
    note = {R package version 3.1.0},
    url = {https://cran.r-project.org/package=varPro},
    pdf = {https://cran.r-project.org/web/packages/varPro/varPro.pdf},
  }