APA (7th ed.) Citation

National Geographic Society (U.S.). Book Division. National Geographic guide to the national parks of the United States. National Geographic Society.

Chicago Style (17th ed.) Citation

National Geographic Society (U.S.). Book Division. National Geographic Guide to the National Parks of the United States. Washington, D.C.: National Geographic Society.

MLA (8th ed.) Citation

National Geographic Society (U.S.). Book Division. National Geographic Guide to the National Parks of the United States. National Geographic Society.

Warning: These citations may not always be 100% accurate.