To cite package ‘lmm’ in publications use:

  Schafer JL (2026). _lmm: Linear Mixed Models_. R package version 1.5,
  <https://CRAN.R-project.org/package=lmm>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {lmm: Linear Mixed Models},
    author = {Joseph L. Schafer},
    year = {2026},
    note = {R package version 1.5},
    url = {https://CRAN.R-project.org/package=lmm},
  }