ANDRADE, J. L.; DE LA BARRERA, E.; REYES-GARC√ćA, C.; RICALDE, M. F.; VARGAS-SOTO, G.; CREVERA, J. C. The acid metabolism crassulacean: diversity, environmental physiology and productivity. Botanical Sciences, n. 81, p. 37 - 50, 15 Dec. 2007.