Allen, J. L. (2008). Annual editions: Environment 07/08 (Twenty-sixth edition.). McGraw-Hill/Dushkin.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रAllen, John L. Annual Editions: Environment 07/08. Twenty-sixth edition. Dubuque, IA: McGraw-Hill/Dushkin, 2008.
एमएलए (8वां संस्करण) प्रशस्ति पत्रAllen, John L. Annual Editions: Environment 07/08. Twenty-sixth edition. McGraw-Hill/Dushkin, 2008.
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