Samuels, G., P. Landrau, Jr., and S. Alers Alers. “Influence of Phosphate Fertilizers on Pineapple Yields”. The Journal of Agriculture of the University of Puerto Rico 40, no. 4 (October 1, 1956): 218–223. Accessed May 1, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/12633.