To cite package ‘xpress’ in publications use:

  Narasimhan B (2026). _xpress: XPRESS Solver Interface Stub_. R
  package version 9.8.0, <https://github.com/bnaras/xpress>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {xpress: XPRESS Solver Interface Stub},
    author = {Balasubramanian Narasimhan},
    year = {2026},
    note = {R package version 9.8.0},
    url = {https://github.com/bnaras/xpress},
  }