Ehrlich, Paul R. Population resources environment : issues in human ecology / Paul R. Ehrlich, Anne H. Ehrlich. - San Francisco, W. H. Freeman 1970. - 383 p. : ill. ; 26 cm. - A Series of books in biology . Includes bibliographical references and index. ISBN: 0716706806 Subjects--Topical Terms: Population.Pollution.Human ecology. Dewey Class. No.: 301.3 / EHP