National Environmental Education Development. National Park Foundation. (1971). Adventure in environment: Teacher's guide. Silver Burdett.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNational Environmental Education Development. National Park Foundation. Adventure in Environment: Teacher's Guide. Morristown, NJ: Silver Burdett, 1971.
एमएलए (9वां संस्करण) प्रशस्ति पत्रNational Environmental Education Development. National Park Foundation. Adventure in Environment: Teacher's Guide. Silver Burdett, 1971.
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