1. Non-pharmaceutical fentanyl-related deaths – Multiple states, April 2005–March 2007;Centers for Disease Control and Prevention;Morbidity and Mortality Weekly Report,2008
2. Notes from the field: Acetyl fentanyl overdose fatalities – Rhode Island, March–May 2013 Weekly August 30;Centers for Disease Control and Prevention;Morbidity and Mortality Weekly Report,2013
3. Alarming rise in fatal overdoses in Estonia;Denissov,2014
4. EMCDDA Trendspotter study on heroin in Europe;European Monitoring Centre for Drugs and Drug Addiction,2011