J. A. Zavala-Hurtado, P. L. Valverde, A. Díaz-Solís, F. Vite, y E. Portilla, «Vegetation-environment relationships based on a life-forms c1assification in a semiarid region of Tropical Mexico», Rev. Biol. Trop., vol. 44, n.º 2A, pp. 581–590, ago. 1996.