Columbia subject headings:
Harvard subject headings:
Chang, Po-go, -846--Anecdotes.
Merchant marine--Korea--History--Anecdotes.
Silla (Kingdom)--Commerce--History--Anecdotes.
Princeton subject headings:
Chang, Po-go, -846.
Merchant marine--Korea--History--To 1500.
Seafaring life--Korea--History--To 1500.
Shipping--Korea--History--To 1500.
Trade routes--Korea (South)--History--To 1500.