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Apeldoorn AT, Ostelo RW, van Helvoirt H, Fritz JM, Knol DL, van Tulder MW, de Vet HC.Apeldoorn AT, et al. Among authors: knol dl.Spine (Phila Pa 1976). 2012 Jul 15;37(16):1347-56. doi: 10.1097/BRS.0b013e31824d9f2b.Spine (Phila Pa 1976). 2012.PMID: 22333955Clinical Trial.
van der Voort LF, Vennegoor A, Visser A, Knol DL, Uitdehaag BM, Barkhof F, Oudejans CB, Polman CH, Killestein J.van der Voort LF, et al. Among authors: knol dl.Neurology. 2010 Oct 5;75(14):1228-33. doi: 10.1212/WNL.0b013e3181f6c556.Neurology. 2010.PMID: 20921509
Heymans MW, van Buuren S, Knol DL, van Mechelen W, de Vet HC.Heymans MW, et al. Among authors: knol dl.BMC Med Res Methodol. 2007 Jul 13;7:33. doi: 10.1186/1471-2288-7-33.BMC Med Res Methodol. 2007.PMID: 17629912Free PMC article.