1. DARK Classics in Chemical Neuroscience: Morphine
2. Hogshire, J. (2009) Opium for the Masses: Harvesting Nature’s Best Pain Medication, pp 1–194, Feral House, Port Townsend, WA.
3. Booth, M. (1996) Opium: A History, pp 1–359, Simon & Schister Ltd, Great Britain.