Lugo-López, M.A. and Pérez-Escolar, R. 1969. Attempts to Explain the Variability in the Cation-Exchange Capacity of Soils in Terms of Particle Size and Organic-Matter Levels. The Journal of Agriculture of the University of Puerto Rico. 53, 4 (Oct. 1969), 369–373. DOI:https://doi.org/10.46429/jaupr.v53i4.11150.