Baltuille Martín, J. M., P. Schnell Quiertant, and F. J. Rubio Pascual. “Landscape, Geology and Defensive Architecture of the Spanish Civil War in the SW Sector of the Guadarrama Range. A New Methodology for Geological-Archaeological Research”. Boletín Geológico Y Minero, vol. 131, no. 4, Dec. 2020, pp. 539-57, doi:10.21701/bolgeomin.131.4.002.