Pérez, A. and Vargas, D. (1977) “Effect of Fertilizer Level and Planting Distance on Soil pH, Growth, Fruit Size, Disease Incidence, Yield, and Profit of Two Papaya Varieties”, The Journal of Agriculture of the University of Puerto Rico, 61(1), pp. 68–76. doi: 10.46429/jaupr.v61i1.10480.