Andrew Zusevics, J., and John J. La Brecque. “MICRONUTRIENT CONTENT OF TROPICAL SOILS OF THE UPPER ORINOCO RIVER BASIN”. The Journal of Agriculture of the University of Puerto Rico 64, no. 3 (July 1, 1980): 363–367. Accessed April 19, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/10225.