Yagüe, A., S. Valls, E. Vázquez, and V. Kuchinow. “Use of Dry Sludge from Waste Water Treatment Plants As an Additive in Prefabricated Concrete Brick”. Materiales De Construcción, vol. 52, no. 267, Sept. 2002, pp. 31-41, doi:10.3989/mc.2002.v52.i267.324.