To cite package ‘nnls’ in publications use:

  Mullen KM, van Stokkum IHM (2024). _nnls: The Lawson-Hanson Algorithm
  for Non-Negative Least Squares (NNLS)_. R package version 1.6,
  <https://CRAN.R-project.org/package=nnls>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {nnls: The Lawson-Hanson Algorithm for Non-Negative Least Squares
(NNLS)},
    author = {Katharine M. Mullen and Ivo H. M. {van Stokkum}},
    year = {2024},
    note = {R package version 1.6},
    url = {https://CRAN.R-project.org/package=nnls},
  }