Pursell, C. W. (1973). From conservation to ecology: The development of environmental concern. Crowell.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPursell, Carroll W. From Conservation to Ecology: The Development of Environmental Concern. New York: Crowell, 1973.
एमएलए (9वां संस्करण) प्रशस्ति पत्रPursell, Carroll W. From Conservation to Ecology: The Development of Environmental Concern. Crowell, 1973.
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