Abadie, Alberto, Alexis Diamond, and Jens Hainmueller. “Synth: An R Package for Synthetic Control Methods in Comparative Case Studies”. Journal of Statistical Software 42, no. 13 (June 14, 2011): 1–17. Accessed October 7, 2022. https://www.jstatsoft.org/index.php/jss/article/view/v042i13.