Vicente-Chandler, José, Servando Silva, and Jacinto Figarella. “Some Limitations in the Use of the Air Picnometer for Soil-Porosity, Soil-Moisture, and Particle-Density Determinations”. The Journal of Agriculture of the University of Puerto Rico 40, no. 3 (July 1, 1956): 179–188. Accessed November 30, 2022. https://revistas.upr.edu/index.php/jaupr/article/view/13799.