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शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रUnited States. Superintendent of Documents. Environmental Protection. Washington, DC: U.S. G.P.O., Supt. of Docs, 1994.
एमएलए (9वां संस्करण) प्रशस्ति पत्रUnited States. Superintendent of Documents. Environmental Protection. U.S. G.P.O., Supt. of Docs, 1994.
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