To cite package ‘Matrix’ in publications use:

  Bates D, Maechler M, Jagan M (2024). _Matrix: Sparse and Dense Matrix
  Classes and Methods_. R package version 1.7-1,
  <https://CRAN.R-project.org/package=Matrix>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {Matrix: Sparse and Dense Matrix Classes and Methods},
    author = {Douglas Bates and Martin Maechler and Mikael Jagan},
    year = {2024},
    note = {R package version 1.7-1},
    url = {https://CRAN.R-project.org/package=Matrix},
  }