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Peiró S, Librero J, Ridao M, Bernal-Delgado E; Grupo de Variaciones en la Práctica Médica en el Sistema Nacional de Salud.Peiró S, et al. Among authors: librero j.Gac Sanit. 2010 Jan-Feb;24(1):6-12. doi: 10.1016/j.gaceta.2009.06.008. Epub 2009 Oct 31.Gac Sanit. 2010.PMID: 19880219Free article.Spanish.