1. United Nations Office on Drugs and Crime. The Challenge of New Psychoactive Substances. http://www.unodc.org/documents/scientific/NPS_2013_SMART.pdf (26 June 2015, date last accessed).
2. European Drug Report 2015. Trends and Developments. http://www.emcdda.europa.eu/attachements.cfm/att_239505_EN_TDAT15001ENN.pdf (26 June 2015, date last accessed).
3. New psychoactive substances in Europe. An Update From the EU Early Warning System (March 2015). http://www.emcdda.europa.eu/attachements.cfm/att_235958_EN_TD0415135ENN.pdf (26 June 2015, date last accessed).
4. Drug Misuse: Findings From the 2013 to 2014 Crime Survey for England and Wales. https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/335989/drug_misuse_201314.pdf (26 June 2015, date last accessed).
5. ‘Our favourite drug’: prevalence of use and preference for mephedrone in the London night-time economy 1 year after control