Abruña, F. et al. 1983. Crop Response to Soil Acidity Factors in Ultisols and Oxisols in Puerto Rico. VI. Grain Sorghum. The Journal of Agriculture of the University of Puerto Rico. 67, 1 (Jan. 1983), 28–38. DOI:https://doi.org/10.46429/jaupr.v67i1.7688.