Rodríguez, S. J., R. Bosque-Lugo, R. Pérez-Pérez, and A. Rodríguez-Cabrera. “Yield Response of the Puerto Rico and Columnaris Coffee Cultivars in Two Latosols of Puerto Rico, As Affected by Different Levels of Nitrogen, Phosphorus, Potassium, and Lime”. The Journal of Agriculture of the University of Puerto Rico, vol. 48, no. 3, July 1964, pp. 255-62, doi:10.46429/jaupr.v48i3.12993.