APA (7th ed.) Zitazioa
Brown, L. R., & Starke, L. (1991). State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society.
Chicago Style (17th ed.) Zitazioa
Brown, Lester R., eta Linda Starke. State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. 1991.
MLA (9th ed.) Zitazioa
Brown, Lester R., eta Linda Starke. State of the World 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. 1991.
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