Boyce, D. S., and A. A. Pérez-Fonrodona. “Observations on the Resistance to Vertical Airflow of Green and Parchment Coffees”. The Journal of Agriculture of the University of Puerto Rico 46, no. 1 (January 1, 1962): 55–64. Accessed July 18, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/12294.