Rubin, D. B. (1974). "Estimating causal effects of treatments in randomized and nonrandomized studies". Journal of Educational Psychology. 66 (5): 688–701. doi:10.1037/h0037350. S2CID52832751.
Rubin, D. B. (1974). "Estimating causal effects of treatments in randomized and nonrandomized studies". Journal of Educational Psychology. 66 (5): 688–701. doi:10.1037/h0037350. S2CID52832751.