References
- Halikas J. A., Rimmer J. D. Predictors of multiple drug abuse. Arch. Gen. Psychiatry 1974; 31: 414–418
- Whitehead P. C, Smart R., LaForest L. Multiple drug use among marijuana smokers in Eastern Canada. Int. J. Addict. 1972; 7(1)179–190
- Single E., del Kan D., Faust R. Patterns of multiple drug use in high school. J. Health Soc. Behav. 1974; 15(4)344–357