References
- Peck Baey Lian. President. 1978, Singapore Anti-Narcotics Association Personal communication
- The epidemiology of heroin and other narcotics, J. N. Rittenhouse. U.S. Government Printing Office, Washington, D.C. 1977, NIDA Research Monograph 16
- Senate U. S. Marihuana-Hashish Epidemic and its Influence on United States Security. U.S. Government Printing Office, Washington, D.C 1975
- Wardlaw G. Drug Use and Crime. Australian Institute of Criminology, Canberra 1978