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Van Den Berg C, Smit C, Van Brussel G, Coutinho R, Prins M; Amsterdam Cohort.Van Den Berg C, et al. Among authors: smit c.Addiction. 2007 Sep;102(9):1454-62. doi: 10.1111/j.1360-0443.2007.01912.x.Addiction. 2007.PMID: 17697278Free PMC article.
de Vries HJ, van der Bij AK, Fennema JS, Smit C, de Wolf F, Prins M, Coutinho RA, Morré SA.de Vries HJ, et al. Among authors: smit c.Sex Transm Dis. 2008 Feb;35(2):203-8. doi: 10.1097/OLQ.0b013e31815abb08.Sex Transm Dis. 2008.PMID: 18091565