Evaluating the drug use "gateway" theory using cross-national data: Consistency and associations of the order of initiation of drug use among participants in the WHO World Mental Health Surveys.

L Degenhardt, L Dierker, WT Chiu, et al.
Ronald C. Kessler
Drug and Alcohol Dependence
http://www.ncbi.nlm.nih.gov/pubmed/?term=Evaluating%20the%20drug%20use%20%22gateway%22%20theory%20using%20cross-national%20data%3A%20Consistency%20and%20associations%20of%20the%20order%20of%20initiation%20of%20drug%20use%20among%20participants%20in%20the%20WHO%20World%20Mental%20Health%20Surveys.