@book{503525,
	author = {Ehrlich, Paul R. and Ehrlich, Anne H.},
	title = {Population resources environment :},
	publisher = {W. H. Freeman,},
	year = {[1970].},
	series = {A Series of books in biology},
	address = {San Francisco :},
	note = {Third ed. published in 1977 under title: Ecoscience.}
}