@book{42003,
	author = {Nebel, Bernard J. and DÁVILA, Francisco Javier},
	title = {Ciencias ambientales  ecología y desarrollo sostenible.},
	publisher = {Pearson},
	year = {1999},
	series = {Universitarios},
	address = {México D.F. (México)},
	edition = {6a. ed.}
}