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Wettergren L, Hedlund Lindberg M, Kettis Å, Glimelius B, Ring L.Wettergren L, et al. Among authors: kettis a.BMC Med Res Methodol. 2014 Oct 9;14:115. doi: 10.1186/1471-2288-14-115.BMC Med Res Methodol. 2014.PMID: 25300493Free PMC article.