Andrade, J. L., E. de la Barrera, C. Reyes-García, M. F. Ricalde, G. Vargas-Soto, and J. C. Crevera. “The Acid Metabolism Crassulacean: Diversity, Environmental Physiology and Productivity”. Botanical Sciences, no. 81, Dec. 2007, pp. 37 -50, doi:10.17129/botsci.1764.