Eckholm, E. P. (1982). Down to earth: Environment and human needs. East-west Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रEckholm, Erik P. Down to Earth: Environment and Human Needs. East-west Press, 1982.
एमएलए (9वां संस्करण) प्रशस्ति पत्रEckholm, Erik P. Down to Earth: Environment and Human Needs. East-west Press, 1982.
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