Oxford. Holland, P. W., 1986. «Statistics and Causal Inference». Journal of the American Statistical Association, 81(396): 945-960. DOI: <10.2307/2289064>.
Matthews, J. N. S., 2006. Introduction to Randomized Controlled Clinical Trials. Chapman & Hall/CRC. Boca Raton, USA.
Rubin, D. B., 1974. «Estimating Causal Effects of Treatments in Randomized and Non-Randomized Studies». Journal of Educational Psychology,...