Columbia subject headings:
Harvard subject headings:
Chang, Po-go, -846
Korea--Commerce--History.
Korea--Economic conditions--To 935
Merchant marine--Korea--History.
Seafaring life--Korea--History.
Shipping--Korea--History.
Trade routes--Korea (South)--History.
Princeton subject headings:
Chang, Po-go, -846.
Korea--Commerce--History.
Korea--Economic conditions--To 935.
Merchant marine--Korea--History.
Seafaring life--Korea--History.
Shipping--Korea--History.
Trade routes--Korea (South)--History.