Worldwatch Institute, Gardner, G. T., Bright, C., & Starke, L. (1991). State of the world, 1991: A worldwatch institute report on progress toward a sustainable society (First edition.). W.W. Norton & Co..
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रWorldwatch Institute, Gary T. Gardner, Chris Bright, और Linda Starke. State of the World, 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. First edition. New York ; London: W.W. Norton & Co., 1991.
एमएलए (8वां संस्करण) प्रशस्ति पत्रWorldwatch Institute, et al. State of the World, 1991: A Worldwatch Institute Report on Progress Toward a Sustainable Society. First edition. W.W. Norton & Co., 1991.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.