To cite package ‘fctutils’ in publications use:

  Guo K (2025). _fctutils: Advanced Factor Manipulation Utilities_. R
  package version 0.0.8, <https://github.com/guokai8/fctutils>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {fctutils: Advanced Factor Manipulation Utilities},
    author = {Kai Guo},
    year = {2025},
    note = {R package version 0.0.8},
    url = {https://github.com/guokai8/fctutils},
  }