APA (7th ed.) Zitazioa
Brown, L. R. (1991). State of the world 1991: A worldwatch institute report on progress toward a sustainable society. W.W. Norton & Co..
Chicago Style (17th ed.) Zitazioa
Brown, Lester R. State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. New York: W.W. Norton & Co., 1991.
MLA (9th ed.) Zitazioa
Brown, Lester R. State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. W.W. Norton & Co., 1991.
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