@book{78486,
	author = {Pingali, Prabhu L. and Heisey, Paul W.},
	title = {Cereal crop productivity in developing countries :},
	publisher = {Centro Internacional de Mejoramiento de Maíz y Trigo,},
	year = {1999.},
	series = {Economics. Working paper},
	address = {México, D.F. :}
}