Varas, M. J., E. Molina, and M. A. Vicente. “Ornamental Sandstones Used in Ciudad Rodrigo, Salamanca: Petrographic and Chemical Characterization of the Quarry Materials”. Materiales de Construcción 52, no. 266 (June 30, 2002): 33–53. Accessed March 29, 2024. https://materconstrucc.revistas.csic.es/index.php/materconstrucc/article/view/333.