We have information from several sources:
Native Cultivars of Cactus Pear in México—C. Mondragon-Jacobo and S. Perez-Gonzalez
Mediterranean Fruits—Joan Tous and Louise Ferguson
Commercializing Mesquite, Leucaena, and Cactus in Texas—Peter Felker
Low Input Agricultural Systems Based on Cactus Pear for Subtropical Semiarid Environments—Candelario Mondragon Jacobo
Magness, J.R., G.M. Markle, C.C. Compton. 1971. Food and feed crops of the United States.