@book{20030,
	author = {Laird, Reggie J. and Turrent Fernández, Antonio.},
	title = {La investigación en productividad de agrosistemas},
	publisher = {Colegio de Postgraduados,},
	year = {1993},
	series = {Cuaderno de edafología},
	address = {Montecillo, Méx. :}
}