Columbia subject headings:
Harvard subject headings:
America--Antiquities.
America--Discovery and exploration--Chinese.
America--Discovery and exploration--Pre-Columbian.
Bering Land Bridge.
Explorers--America--History.
Explorers--North America--History.
North America--Discovery and exploration.
Ocean travel--History
Princeton subject headings:
America--Discovery and exploration.
Explorers--America--History.
Explorers--North America--History.
North America--Discovery and exploration.