(2020). Secrets of the National Parks: The expert's guide to the best experiences beyond the tourist trail (Second edition.). National Geographic Society.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSecrets of the National Parks: The Expert's Guide to the Best Experiences Beyond the Tourist Trail. Second edition. Washington, D.C.: National Geographic Society, 2020.
एमएलए (8वां संस्करण) प्रशस्ति पत्रSecrets of the National Parks: The Expert's Guide to the Best Experiences Beyond the Tourist Trail. Second edition. National Geographic Society, 2020.
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