The initial database search resulted in 64 publications referring to the four cannabis screening instruments in the title, the abstract or the keywords. These references were downloaded to a reference database and abstracts were screened to identify those relevant to the research question. Exclusion of non-relevant papers (i. e. predominantly biochemical or pharmacological topics, studies on the effects of cannabis use on different behavioural outcomes), non-empirical papers and studies only using but not validating the target instruments left eight publications for further consideration. Scanning the reference lists and the World Wide Web led to the identification of another four papers, adding up to a total of 12 selected publications for this review.
