National Geographic Society (U.S.) Special Publications Division. (1979). Mysteries of the ancient world. The Society.
Chicago-viite (17. p.)National Geographic Society (U.S.) Special Publications Division. Mysteries of the Ancient World. Washington: The Society, 1979.
MLA-viite (9. p.)National Geographic Society (U.S.) Special Publications Division. Mysteries of the Ancient World. The Society, 1979.
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