To cite package ‘RCPA4’ in publications use:

  Edwards B (2026). _RCPA4: Data and Functions for "An R Companion to
  Political Analysis, Fourth Edition"_. R package version 1.0.0,
  <https://CRAN.R-project.org/package=RCPA4>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {RCPA4: Data and Functions for "An R Companion to Political Analysis,
Fourth Edition"},
    author = {Barry C. Edwards},
    year = {2026},
    note = {R package version 1.0.0},
    url = {https://CRAN.R-project.org/package=RCPA4},
  }