Hancock, G. (2019). America before: The key to Earth's lost civilization (First edition.). St. Martin's Press.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रHancock, Graham. America Before: The Key to Earth's Lost Civilization. First edition. New York: St. Martin's Press, 2019.
एमएलए (8वां संस्करण) प्रशस्ति पत्रHancock, Graham. America Before: The Key to Earth's Lost Civilization. First edition. St. Martin's Press, 2019.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.