1. The Epidemiology of Opiate Addiction in the United States;Ball,1970
2. A 2.5 year follow-up of cocaine use among treated opioid addicts;Kosten;Arch Gen Psychiatry,1987
3. Epidemiologists discuss cocaine abuse trends;National Institute on Drug Abuse;Natl Inst Drug Abuse,1987
4. Use of nonnarcotic drugs by narcotic addicts;Nurco,1985