M. Zschöck, A. El-Sayed, N. Eissa, C. Lämmler, and H. Castañeda Vazquez, “Penicillin G and oxacillin resistance in Staphylococcus aureus strains isolated from bovine subclinical mastitis”, Vet Mex OA, vol. 42, no. 3, Aug. 2013.