Columbia subject headings:
Free trade--Mexico.
Free trade--United States.
Mexico--Commercial policy.
United States--Commercial policy.
Harvard subject headings:
Free trade--Mexico
Free trade--United States
Mexico--Commerce--United States.
Mexico--Commercial policy.
United States--Commerce--Mexico.
United States--Commercial policy.
Princeton subject headings:
Free trade--Mexico.
Free trade--United States.
Mexico--Commercial policy.
United States--Commercial policy.