1. Brecher EM (1972) In: Licit and illicit drugs. Consumers Union, Mount Vernon, New York
2. British Home Office (1985) Tackling drag misuse: A summary of the Government strategy. Home Office Publications
3. Bundesgesundheitsamt: Mitteilung des Bundesgesundheitsamtes vom 20. 6. 1985 (personal communication)
4. Cassel RN (1971) Drug abuse education. The Christopher Publishing House, North Quincy, Mass, p 286
5. Isbell H, Chrusciel TL (1970) Dependence liability of non-narcotic drugs. Suppl to vol 43, Bull of WHO, Geneve, p 5