Columbia subject headings:
Canada--Commerce--United States.
Canada--Foreign relations--United States.
Terrorism--North America--Prevention--International cooperation.
United States--Commerce--Canada.
United States--Foreign relations--Canada.
Harvard subject headings:
Canada--Commerce--United States.
Canada--Foreign relations--United States.
Terrorism--North America--Prevention--International cooperation.
United States--Commerce--Canada.
United States--Foreign relations--Canada.
Princeton subject headings:
Canada--Commerce--United States.
Canada--Foreign relations--United States.
Terrorism--North America--Prevention--International cooperation.
United States--Commerce--Canada.
United States--Foreign relations--Canada.