Prieto Mendez, Judith, et al. “Correlation of Moisture, PH and Zeta Potential (z) in Sandy-Clay-Loam Soils of the Southern State of Hidalgo, Mexico”. Asian Journal of Chemistry, vol. 26, no. 10, May 2014, pp. 3001-5, doi:10.14233/ajchem.2014.16343.