@book{4928,
	author = {Sosa, Romeo. and Congreso Nacional de Fitogenética (},
	title = {Los sistemas de producción agrícola en la zona cerealera - papera de Perote-Los Altos},
	publisher = {UACH. Centro Regional Universitario Oriente,},
	year = {[1990?]},
	address = {Huatusco, Ver. :},
	note = {55-59}
}