Ehrlich, Paul R. Population resources environment : issues in human ecology / Paul R. Ehrlich and Anne H. Ehrlich. - San Francisco : W. H. Freeman , 1970. - 383 p. : illus. 26 cm. - A Series of books in biology . Third ed. published in 1977 under title: Ecoscience. Bibliography: p. [360]-363. ISBN: 0716706806 LCCN: 75103067 Subjects--Topical Terms: Population.Pollution.Human ecology. LC Class. No.: HB871 / .E35 Dewey Class. No.: 304.6 / EHP 1970