To cite package ‘optextras’ in publications use:

  Nash JC (2026). _optextras: Tools to Support Optimization Possibly
  with Bounds and Masks_. R package version 2019-12.4,
  <https://github.com/cranhaven/cranhaven.r-universe.dev>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {optextras: Tools to Support Optimization Possibly with Bounds and Masks},
    author = {John C Nash},
    year = {2026},
    note = {R package version 2019-12.4},
    url = {https://github.com/cranhaven/cranhaven.r-universe.dev},
  }