Columbia subject headings:
Merchant marine--United States.
Shipbuilding--United States.
Shipping--United States.
United States--Commerce.
Harvard subject headings:
Merchant marine--United States
Shipbuilding--United States
Shipping--United States
United States--Commerce.
Princeton subject headings:
Merchant marine--United States.
Shipbuilding--United States.
Shipping--United States.
United States--Commerce.