Columbia subject headings:
Free trade--Western Hemisphere.
South America--Foreign economic relations--United States.
South America--Foreign relations--United States.
United States--Foreign economic relations--South America.
United States--Foreign relations--South America.
Harvard subject headings:
Free trade--Western Hemisphere.
South America--Foreign economic relations--United States.
South America--Foreign relations--United States.
United States--Foreign economic relations--South America.
United States--Foreign relations--South America.
Princeton subject headings:
Free trade--Western Hemisphere.
South America--Foreign economic relations--United States.
South America--Foreign relations--United States.
United States--Foreign economic relations--South America.
United States--Foreign relations--South America.