To cite package ‘SPAS’ in publications use:

  Schwarz CJ (2025). _SPAS: Stratified-Petersen Analysis System_. R
  package version 2025.2.1, <https://CRAN.R-project.org/package=SPAS>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {SPAS: Stratified-Petersen Analysis System},
    author = {Carl James Schwarz},
    year = {2025},
    note = {R package version 2025.2.1},
    url = {https://CRAN.R-project.org/package=SPAS},
  }