Abruña, F., E. Rivera, and J. A. Rodríguez-García. “Crop Response to Soil Acidity Factors in Ultisols and Oxisols in Puerto Rico. X. Pigeon Peas”. The Journal of Agriculture of the University of Puerto Rico 68, no. 4 (October 1, 1984): 433–443. Accessed December 22, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/7313.