@book{76733,
	author = {Valdovinos Ayala, José Hermenegildo.},
	title = {Estudio de la asociación maíz-papa en la zona de agricultura intensiva del Carst-Chamula, Chiapas, México},
	publisher = {El autor,},
	year = {1998.},
	address = {Chapingo, Méx. :}
}