Columbia subject headings:
Canada--Commerce--United States--Congresses.
Canada--Commercial treaties--Congresses.
Free trade--Congresses.
United States--Commerce--Canada--Congresses.
United States--Commercial treaties--Congresses.
Harvard subject headings:
Canada. Treaties, etc. 1988 January 2--Congresses.
Duty-free importation--Law and legislation--Canada--Congresses.
Duty-free importation--Law and legislation--United States--Congresses.
Free trade--Canada--Congresses
Free trade--United States--Congresses
Tariff--Law and legislation--Canada--Congresses.
Tariff--Law and legislation--United States--Congresses.
Princeton subject headings:
Canada--Commerce--United States--Congresses.
Canada--Commercial treaties--Congresses.
Free trade--Canada--Congresses.
Free trade--United States--Congresses.
United States--Commerce--Canada--Congresses.
United States--Commercial treaties--Congresses.