Columbia subject headings:
Organized crime--Europe.
Organized crime--United States.
Triads (Organized crime)--Europe.
Triads (Organized crime)--United States.
Harvard subject headings:
Organized crime--Europe
Organized crime--United States
Triads (Organized crime)--Europe.
Triads (Organized crime)--United States.
Princeton subject headings:
Triads (Gangs)