Columbia subject headings:
Drug control--United States.
Foreign trade regulation--United States.
Opium trade--Australia.
Opium trade--India.
Opium trade--Turkey.
Opium trade--United States.
Harvard subject headings:
Princeton subject headings:
Drug control--United States.
Foreign trade regulation--United States.
Opium trade--Australia.
Opium trade--India.
Opium trade--Turkey.