World resources 1990-91 : a report / by the World Resources Institute in collaboration with the United Nations Environment Programme and and the United Nations Development Programme. World Resources Institute. United Nations Environment Programme. United Nations Development Programme. Natural resources. Environmental policy. Economic policy Environmental aspects. 333.7 WOR Includes bibliographical references and index. New York : Oxford Univ. Press, 1990. 1990. 1990 Text xiv, 383 p. : eng