Abruña, Fernando, and José Vicente. “Refinement of a Quantitative Method for Determining the Lime Requirements of Soils”. The Journal of Agriculture of the University of Puerto Rico 39, no. 1 (January 1, 1955): 41–45. Accessed June 30, 2024. https://revistas.upr.edu/index.php/jaupr/article/view/12697.