Comparison of virusneutralization tests against four strains of BVDV (BVDV-1 and BVDV-2) in cattle naturally infected in Brazil - Ribeiro, C. P; Della Libera, Alice Maria Melville Paiva; Jordão, R. S; Okuda, L. H; Pituco, E. M (Congress of European Microbiologists, 2011)