APA (7e ed.) Bronvermelding

National Geographic Society. (1978). The heart of the Grand Canyon: / Grand Canyon Park, Arizona. National Geographic Magazine.

Chicago (17e ed.) Bronvermelding

National Geographic Society. The Heart of the Grand Canyon: / Grand Canyon Park, Arizona. Washigton, Estados Unidos: National Geographic Magazine, 1978.

MLA (9e ed.) Bronvermelding

National Geographic Society. The Heart of the Grand Canyon: / Grand Canyon Park, Arizona. National Geographic Magazine, 1978.