1. The new drug phenomenon;Brandt;Drug Test. Anal.,2014
2. European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) New psychoactive substances in Europe. An update from the EU Early Warning System. Lisbon 2015 http://www.emcdda.europa.eu/publications/2015/new-psychoactive-substances
3. Synthetics Monitoring: Analyses, Reporting and Trends (SMART) Global SMART update: legal responses to NPS: multiple approaches to a multi-faceted problem 2015 http://www.unodc.org/documents/scientific/Global_SMART_Update_14-web.pdf
4. United Nations Office on Drugs and Crime (UNODC) The challenge of new psychoactive substances 2013 www.unodc.org/documents/scientific/NPS_2013_SMART.pdf
5. Khat and synthetic cathinones: a review;Valente;Arch. Toxicol.,2014