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Fietta A, Fortunato A, Dos Santos C, Grassi F, Siccardi AG.Fietta A, et al. Among authors: grassi f.Infect Immun. 1981 Sep;33(3):704-9. doi: 10.1128/iai.33.3.704-709.1981.Infect Immun. 1981.PMID: 6793516Free PMC article.