A. Aguillón Robles, M. Tristán González, R. A. López Doncel, M. E. García Arreola, J. de L. Almaguer Rodríguez., and R. C. Maury, “Trace elements geochemistry and origin of volcanic units from the San Luis Potosí and Río Santa María volcanic fields, Mexico: The bearing of ICP-QMS data”, Geofis Int, vol. 51, no. 3, p. 293-­308, Jul. 2012.