Weigler, H., and S. Karl. “Manufacture, Properties, Utilisation, Strength and Apparent Density of Lightweight Reinforced Concrete”. Materiales de Construcción 21, no. 142 (June 30, 1971): 71–80. Accessed April 29, 2024. https://materconstrucc.revistas.csic.es/index.php/materconstrucc/article/view/1511.