Jeffries, C. D., J. A. Bonnet, and F. Abruña. “The Constituent Minerals of Some Soils of Puerto Rico”. The Journal of Agriculture of the University of Puerto Rico 37, no. 2 (April 1, 1953): 114–139. Accessed April 19, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/12756.