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Mokkink LB, Terwee CB, Patrick DL, Alonso J, Stratford PW, Knol DL, Bouter LM, de Vet HC.Mokkink LB, et al. Among authors: terwee cb.Qual Life Res. 2010 May;19(4):539-49. doi: 10.1007/s11136-010-9606-8. Epub 2010 Feb 19.Qual Life Res. 2010.PMID: 20169472Free PMC article.