Nawaz, Rab, et al. “Interactions Between Acidic (Al3+, Fe2+) and Basic (Ca2+, Mg2+) Cations in Oxisol and Ultisol under Acidification Induced by Simulated Acid Rain”. Asian Journal of Chemistry, vol. 26, no. 15, July 2014, pp. 4794-00, doi:10.14233/ajchem.2014.16229.