HO, D.; IMAI, K.; KING, G.; STUART, E. A. MatchIt: Nonparametric Preprocessing for Parametric Causal Inference. Journal of Statistical Software, [S. l.], v. 42, n. 8, p. 1–28, 2011. DOI: 10.18637/jss.v042.i08. Disponível em: https://www.jstatsoft.org/index.php/jss/article/view/v042i08. Acesso em: 4 dec. 2021.