Columbia subject headings:
September 11 Terrorist Attacks, 2001.
Terrorism--United States.
United States--Relations--Western Hemisphere.
Western Hemisphere--Relations--United States.
Harvard subject headings:
September 11 Terrorist Attacks, 2001
Terrorism--United States
United States--Relations--Western Hemisphere.
Western Hemisphere--Relations--United States.
Princeton subject headings:
September 11 Terrorist Attacks, 2001.
Terrorism--United States.
United States--Relations--Western Hemisphere.
Western Hemisphere--Relations--United States.