Calmus, T. et al. 2018. A multi-elemental study to establish the natural background and geochemical anomalies in rocks from the Sonora river upper basin, NW Mexico. Revista Mexicana de Ciencias Geológicas. 35, 2 (Jul. 2018), 158–167. DOI:https://doi.org/10.22201/cgeo.20072902e.2018.2.605.