Reyna, J. L. (1969) «Hubert M. Blalock Jr. Causal inferences in non-experimental research. Chapel Hill, [N. C.] : The University of North Carolina Press, 1964. ix, 200 p»., Estudios Demográficos y Urbanos, 3(03), pp. 384–385. doi: 10.24201/edu.v3i03.87.