Columbia subject headings:
Black Sea--Navigation--History.
Merchant ships--Black Sea--History.
Venice (Italy)--Commerce--Black Sea Region--History.
Harvard subject headings:
Black Sea Region--Commerce--Italy--Venice--History.
Black Sea--Navigation--History.
Merchant marine--Italy--Venice--History.
Merchant ships--Black Sea--History.
Merchant ships--Italy--Venice--History.
Venice (Italy)--Commerce--Black Sea Region--History.
Princeton subject headings: