Columbia subject headings:
Africa--Commerce--United States.
Foreign trade regulation--United States.
Tariff--Law and legislation--United States.
United States--Commerce--Africa.
Harvard subject headings:
Africa--Commerce--United States.
Foreign trade regulation--United States.
Tariff--Law and legislation--United States.
United States--Commerce--Africa.
Princeton subject headings:
Africa--Commerce--United States.
Foreign trade regulation--United States.
Tariff--Law and legislation--United States.
United States--Commerce--Africa.