To cite 'spantest' in publications use:

  Ardia, D., Seguin, B. (2025). spantest: Mean-Variance Spanning Tests
  in R.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {spantest: Mean-Variance Spanning Tests in R},
    author = {David Ardia and Benjamin Seguin},
    year = {2025},
    organization = {CRAN},
  }