Enríquez-Almeida, A. A., and M. de J. Quezada-Ochoa. “Chemical Footprint of Identifying Elements in the Nambija and Zaruma-Portovelo Mining Districts”. FIGEMPA: Investigación Y Desarrollo, vol. 11, no. 1, July 2021, pp. 12-20, doi:10.29166/revfig.v11i1.2181.