National Geographic Society (U.S.). Special Publications Division. (1983). Preserving America's past. The Society.
Dyfyniad Arddull ChicagoNational Geographic Society (U.S.). Special Publications Division. Preserving America's Past. Washington, D.C: The Society, 1983.
Dyfyniad MLANational Geographic Society (U.S.). Special Publications Division. Preserving America's Past. The Society, 1983.
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