Felker, 2001. Mondragon-Jacobo, C. and Perez-Gonzalez, S. Ed. FAO Plant production and protection papers N°169. FAO, Rome

Felker, P., 2001. Utilization of Opuntia forage in the United States of America. In: Cactus (Opuntia spp.) as forage. Mondragon-Jacobo, C. and Perez-Gonzalez, S. Ed. FAO Plant production and protection papers N°169. FAO, Rome