To cite RStan in publications use:

  Stan Development Team (). RStan: the R interface to Stan. R package
  version 2.35.0.9000. https://mc-stan.org/.

A BibTeX entry for LaTeX users is

  @Misc{,
    title = {{RStan}: the {R} interface to {Stan}},
    author = {{Stan Development Team}},
    note = {R package version 2.35.0.9000},
    url = {https://mc-stan.org/},
  }