1. World Health Organization. Management of substance abuse: cannabis https://www.who.int/substance_abuse/facts/cannabis/en/.
2. Jiang H, Li X, Zhao Y, et al. A new insight into Cannabis sativa (Cannabaceae) utilization from 2500-year-old Yanghai Tombs, Xinjiang, China. J Ethnopharmacol. 2006;108(3):414–22. https://doi.org/10.1016/j.jep.2006.05.034.
3. Drug Enforcement Administration Office of Diversion Control. Schedules of controlled substances. (b) Placement on schedules; findings required. (1) Schedule I. Springfield, Virginia: U.S. Department of Justice; 1970. [Accessed 5 Aug 2016]. Title 21 United States Code (USC) Controlled Substances Act. Subchapter I–Control and enforcement Part B–Authority to control; standards of controlled substances §812. [also known as Controlled Substances Act, 21 United States Code § 812(b)(1), 1970]. Available at: www.deadiversion.usdoj.gov/21cfr/21usc/812.htm.
4. Bennett C. Early/ancient history. In: Holland J, editor. The pot book: a complete guide to cannabis. Rochester: Park Street Press; 2010.
5. Abel EL. Marihuana, the first twelve thousand years. New York: Plenum Press; 1980.