Multiple drug use considered in the light of the stepping-stone hypothesis.
D000661:Amphetamine; D002188:Cannabis; D004335:Drug and Narcotic Control; D000431:Ethanol; D005260:Female; D006801:Humans; D007880:Legislation, Drug; D008238:Lysergic Acid Diethylamide; D008297:Male; D009042:Motivation; D009426:Netherlands; D009892:Opium; D012919:Social Behavior; D019966:Substance-Related Disorders / Q000453:epidemiology; D011795:Surveys and Questionnaires
D000431:Ethanol; D009892:Opium; D008238:Lysergic Acid Diethylamide; D000661:Amphetamine