1. United Nations Office on Drugs and Crime [UNODC]. World drug report 2016. [cited 2019 July 20]. Available from: https://www.unodc.org/doc/wdr2016/WORLD_DRUG_REPORT_2016_web.pdf.
2. United Nations Office on Drugs and Crime [UNODC]. World drug report 2018. [cited 2019 July 20]. Available from: https://www.unodc.org/wdr2018/prelaunch/WDR18_Booklet_1_EXSUM.pdf.
3. Thailand, Ministry of Justice. Office of the narcotics control board. Brief history of drug addiction in. 2017. [cited 2019 May 13]. Available from: https://www.oncb.go.th/Pages/main_old.aspx.
4. Thailand, Ministry of Justice. Office of the narcotics control board. Brief history of drug addiction in. 2015. [cited 2019 June 18]. Available from: https://www.oncb.go.th/Pages/main_old.aspx.
5. Thailand, Ministry of Justice, Office of the Narcotics Control Board. A brief history of drug addiction in. 2014. [cited 2019 July 22]. Available from: https://www.oncb.go.th/Pages/main_old.aspx.