Helen Dwight Reid Educational Foundation. (1971). Journal of Environmental Education. Heldref Publications.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रHelen Dwight Reid Educational Foundation. Journal of Environmental Education. Washington: Heldref Publications, 1971.
एमएलए (8वां संस्करण) प्रशस्ति पत्रHelen Dwight Reid Educational Foundation. Journal of Environmental Education. Heldref Publications, 1971.
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