Rodríguez, S. J., R. Bosque Lugo, R. Pérez-Pérez, and A. Morales Muñoz. “Effect of Planting Distances on Shaded Coffee Yield in Puerto Rico”. The Journal of Agriculture of the University of Puerto Rico, vol. 50, no. 2, Apr. 1966, pp. 82-86, doi:10.46429/jaupr.v50i2.3716.