1. World Drug Report 2013;United Nations Office on Drugs and Crime (UNODC),2013
2. New drugs of abuse on the Web: the role of the Psychonaut Web Mapping Project;Schifano;Riv. Psichiatr.,2010
3. United Nations Office on Drugs and Crime (UNODC), World Drug Report 2017. Vienna. http://www.unodc.org/wdr2017/press/WDR_Press_Release.pdf. (Accessed 31 July 2018).
4. European Centre for Drugs and Drug Addiction (EMCDDA). ESPAD Report 2015. Results from the European School Survey Project on Alcohol and Other Drugs. http://www.espad.org/sites/espad.org/files/ESPAD_report_2015.pdf. (Accessed 31 July 2018).
5. 2016 European Centre for Drugs and Drug Addiction (EMCDDA). European Drug Report 2018. Trends and Developments. http://www.emcdda.europa.eu/system/files/publications/8585/20181816_TDAT18001ENN_PDF.pdf. (Accessed 01 November 2018).