8Takacs T, Gathy I, Machaty Z, et al. Bacterial contamination of the uterus after parturition and its effect on the reproductive performance of cows large scale dairy farms [J]. Theriogenology, 1990, 33 (4): 851-866.
9Eallion L, McMahon K J, et al. Uterus of the cows after parturition: Bacterial content[J].Am J Vet Res, 1968,29:77-78.
10Lioyd Elliontt, McMahon k J, et al Uterus of the cow after Parturition:Bacterial content. [J].Am J Vet Res Vol, 1978,29 :77-81.