To cite package ‘nlme’ in publications use:

  Pinheiro J, Bates D, R Core Team (2026). _nlme: Linear and Nonlinear
  Mixed Effects Models_. R package version 3.1-171,
  <https://svn.r-project.org/R-packages/trunk/nlme/>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {nlme: Linear and Nonlinear Mixed Effects Models},
    author = {José Pinheiro and Douglas Bates and {R Core Team}},
    year = {2026},
    note = {R package version 3.1-171},
    url = {https://svn.r-project.org/R-packages/trunk/nlme/},
  }

  Pinheiro JC, Bates DM (2000). _Mixed-Effects Models in S and S-PLUS_.
  Springer, New York. doi:10.1007/b98882
  <https://doi.org/10.1007/b98882>.

A BibTeX entry for LaTeX users is

  @Book{,
    title = {Mixed-Effects Models in S and S-PLUS},
    author = {José C. Pinheiro and Douglas M. Bates},
    year = {2000},
    publisher = {Springer},
    address = {New York},
    doi = {10.1007/b98882},
  }
