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Dryden R, Williams B, McCowan C, Themessl-Huber M.Dryden R, et al. Among authors: mccowan c.BMC Public Health. 2012 Aug 31;12:723. doi: 10.1186/1471-2458-12-723.BMC Public Health. 2012.PMID: 22938046Free PMC article.Review.