1. What are
NPS? https://www.unodc.org/LSS/Page/NPS (accessed Sept 26, 2018).
2. World Drug Report 2018, https://www.unodc.org/wdr2018/ (accessed Sept 26, 2018).
3. Fentanils
and synthetic cannabinoids: driving greater complexity
into the drug situation—an update from the EU Early Warning
System, www.emcdda.europa.eu, http://www.emcdda.europa.eu/publications/rapid-communications/fentanils-and-synthetic-cannabinoids-ews-update_en (accessed Sept 26, 2018).