Dyfyniad APA

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

Dyfyniad Arddull Chicago

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

Dyfyniad MLA

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

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