Columbia subject headings:
Shipping--United States--Periodicals.
United States. Federal Maritime Commission--Periodicals.
Harvard subject headings:
Merchant marine--United States--Periodicals.
Shipping--United States--Periodicals.
United States. Federal Maritime Commission--Periodicals.
Princeton subject headings:
Merchant marine--United States--Auditing--Statistics--Periodicals.
Periodicals.
Shipping--United States--Auditing--Statistics--Periodicals.
Statistics.
United States. Federal Maritime Commission--Auditing--Statistics--Periodicals.