APA (7th ed.) Citation

National Geographic Society. (1989). National geographic guide to the national parks of the United States (3rd ed.). National Geographic Society.

Chicago Style (17th ed.) Citation

National Geographic Society. National Geographic Guide to the National Parks of the United States. 3rd ed. Washington: National Geographic Society, 1989.

MLA (8th ed.) Citation

National Geographic Society. National Geographic Guide to the National Parks of the United States. 3rd ed. National Geographic Society, 1989.

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