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Jansen JP, Cope S.Jansen JP, et al. Among authors: cope s.BMC Med Res Methodol. 2012 Oct 8;12:152. doi: 10.1186/1471-2288-12-152.BMC Med Res Methodol. 2012.PMID: 23043545Free PMC article.
Cope S, Jansen JP.Cope S, et al.BMC Med Res Methodol. 2013 Dec 1;13:147. doi: 10.1186/1471-2288-13-147.BMC Med Res Methodol. 2013.PMID: 24289277Free PMC article.