Columbia subject headings:
Harvard subject headings:
Africa--Commerce--United States.
Africa--Foreign economic relations--United States.
Investments, American--Africa.
Non-tariff trade barriers--Africa.
United States--Commerce--Africa.
United States--Foreign economic relations--Africa.
Princeton subject headings:
Africa--Commerce--United States.
Africa--Foreign economic relations--United States.
Investments, American--Africa.
Non-tariff trade barriers--Africa.
United States--Commerce--Africa.
United States--Foreign economic relations--Africa.