National Geographic Society. (1978). The heart of the Grand Canyon: / Grand Canyon Park, Arizona. National Geographic Magazine.
Chicagoスタイル(17版)引用形式National Geographic Society. The Heart of the Grand Canyon: / Grand Canyon Park, Arizona. Washigton, Estados Unidos: National Geographic Magazine, 1978.
MLA(9版)引用形式National Geographic Society. The Heart of the Grand Canyon: / Grand Canyon Park, Arizona. National Geographic Magazine, 1978.
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