Pinzón, B., P. Argel, and R. Montenegro. “ESTABLISHMENT FERTILIZATION ON Andropogon Gayanus CIAT 621 AND Centrosema Macrocarpum CIAT 5062ASSOCIATION IN A CHIRIQUI ULTISOL.”. Ciencia Agropecuaria, no. 7, Feb. 1991, pp. 81-88, http://200.46.165.126/index.php/ciencia-agropecuaria/article/view/504.