R. Vélez-Colón, I. Beauchamp de Caloni, and S. Martínez-Garrastazú, “Sapodilla (Manilkara sapota L. V. Rogen, Achras sapota Linn.) variety trials at southern Puerto Rico”, JAUPR, vol. 73, no. 3, pp. 255–264, Jul. 1989.