Varas, M.J., Molina, E. and Vicente, M.A. 2002. Ornamental sandstones used in Ciudad Rodrigo, Salamanca: petrographic and chemical characterization of the quarry materials. Materiales de Construcción. 52, 266 (Jun. 2002), 33–53. DOI:https://doi.org/10.3989/mc.2002.v52.i266.333.