de la Cruz, J. C., J. M. del Campo, and D. Colorado. “Comparative Study on Porosity and Permeability of Conventional Concrete and Concrete With Variable Proportions of Natural Zeolite Additions”. Revista De La Construcción. Journal of Construction, vol. 14, no. 3, Dec. 2015, pp. 70-76, http://146.155.94.136/index.php/RDLC/article/view/13436.