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Menezes AM, Victora CG, Perez-Padilla R; PLATINO Team.Menezes AM, et al.BMC Med Res Methodol. 2004 Jun 17;4:15. doi: 10.1186/1471-2288-4-15.BMC Med Res Methodol. 2004.PMID: 15202950Free PMC article.