Wischers, Gerd. “Initial Calculation of the Compression Strength of Concrete from the Compression Strength of Normalized Cement Mortar, According to DIN 1 164 E (ISO Test Method)”. Materiales de Construcción 20, no. 137 (March 31, 1970): 88–92. Accessed May 2, 2024. https://materconstrucc.revistas.csic.es/index.php/materconstrucc/article/view/1570.