Vicente-Chandler, José, Servando Silva, and Fernando Abruña. “A New Low-Cost Method of Harvesting Coffee in High-Yielding Plantations”. The Journal of Agriculture of the University of Puerto Rico 53, no. 4 (October 1, 1969): 259–267. Accessed April 18, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/11141.