APA (7th ed.) Citation

National Geographic Society (U.S.). (1976). Our continent: A natural history of North America. National Geographic Society.

Chicago Style (17th ed.) Citation

National Geographic Society (U.S.). Our Continent: A Natural History of North America. Washington: National Geographic Society, 1976.

MLA (8th ed.) Citation

National Geographic Society (U.S.). Our Continent: A Natural History of North America. National Geographic Society, 1976.