By Garber, E. D..
New York : McGraw-Hill, 1972 07-022785-3

By Grun, Paul.
New York : Columbia University Press, 1976 0-231-03975-1

By Ryan, Guillermo S..
Buenos Aires : INTA, 1979

By Wilkie, D..
Madrid : Alhambra, 1970

By Sáez, Francisco A..
Washington : OEA, 1978

By Elliot, Fred C..
México : Cecsa, 1967

By Swanson, Carl P..
México : Uteha, 1968

By White, M. J. D..
Buenos Aires : Espasa-Calpe, 1947

Kew : R. Botanic Gardens, 1995 0-947643-95-8