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Calsina-Berna A, Moreno Millán N, González-Barboteo J, Solsona Díaz L, Porta Sales J.Calsina-Berna A, et al.Aten Primaria. 2011 Nov;43(11):568-75. doi: 10.1016/j.aprim.2010.09.006. Epub 2011 Mar 5.Aten Primaria. 2011.PMID: 21382651Free PMC article.Spanish.