Columbia subject headings:
Canada--Commercial policy.
Canada--Commercial treaties.
Free trade.
Great Britain--Commercial policy.
Great Britain--Commercial treaties.
United States--Commercial policy.
United States--Commercial treaties.
Harvard subject headings:
Free trade--Canada--History.
Free trade--Great Britain--History.
Free trade--United States--History.
Princeton subject headings:
Canada--Commercial policy.
Canada--Commercial treaties.
Great Britain--Commercial policy.
Great Britain--Commercial treaties.
United States--Commercial policy.
United States--Commercial treaties.