Herd factors associated with the seroprevalences of four major respiratory pathogens in slaughter pigs from farrow-to-finish pig herdsDominiek Maes, Hubert Deluyker, Marc Verdonck, Frans Castryck, Cora Miry, Bernard Vrijens and Aart de KruifVet. Res., 31 3 (2000) 313-327DOI: https://doi.org/10.1051/vetres:2000122