Columbia subject headings:
Harvard subject headings:
Andes Region--Commerce--United States.
Tariff preferences--Andes Region.
Tariff preferences--Law and legislation--United States.
United States--Commerce--Andes Region.
Princeton subject headings:
Andes Region--Commerce.
Andes Region--Foreign economic relations--United States.
Duty-free importation--United States.
Tariff preferences--United States.
United States--Foreign economic relations--Andes Region.