Columbia subject headings:
Harvard subject headings:
Canada--Foreign economic relations--Mexico.
Canada--Foreign economic relations--United States
Mexico--Foreign economic relations--Canada.
Subnational governments--Foreign economic relations--Canada.
Subnational governments--Foreign relations--Canada.
United States--Foreign economic relations--Canada
Princeton subject headings:
Canada--Foreign economic relations--Mexico.
Canada--Foreign economic relations--United States.
Mexico--Foreign economic relations--Canada.
Subnational governments--Foreign economic relations--Canada.
Subnational governments--Foreign relations--Canada.
United States--Foreign economic relations--Canada.