Columbia subject headings:
Tariff--Law and legislation--United States--Databases.
Tariff--United States--Terminology and classification--Databases.
Harvard subject headings:
Tariff--Law and legislation--United States--Databases.
Tariff--United States--Terminology and classification--Databases.
Princeton subject headings:
Tariff--Law and legislation--United States--Databases.
Tariff--United States--Terminology and classification--Databases.