Fernández Cánovas, M., N. Hurtado Selva, and G. M. Kawiche. 1989. “Influence on the Physical-Mechanical Properties of Portland-Cement Mortar, Have Admixtures of Colophony and Tannin”. Materiales De Construcción 39 (216):15-22. https://doi.org/10.3989/mc.1989.v39.i216.793.