1."Heroin Century", Tom Carnwath, Ian Smith; Routledge, 2002 page 8
2. Heroin Century Book by Tom Carnwath, Ian Smith; Routledge, 2002 page 15
3.Heroin Century Book by Tom Carnwath, Ian Smith; Routledge, 2002 page 16
4. "Opium: A History" Martin H. Levinson; ETC.: A Review of General Semantics, Vol. 55, 1998
5. "A Hundred-Year Habit" by Ian Scott; History Today, Vol. 48, June 1998