To cite scpi in publications use:

  Matias D. Cattaneo, Yingjie Feng, Filippo Palomba, Roc{'i}o Titiunik
  (2025). scpi: Uncertainty Quantification for Synthetic Control
  Methods. Journal of Statistical Software, 113(1), 1-38.
  doi:10.18637/jss.v113.i01

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{scpi}: Uncertainty Quantification for Synthetic Control Methods},
    author = {Matias D. Cattaneo and Yingjie Feng and Filippo Palomba and Roc{\'i}o Titiunik},
    journal = {Journal of Statistical Software},
    year = {2025},
    volume = {113},
    number = {1},
    pages = {1--38},
    doi = {10.18637/jss.v113.i01},
  }