R. G. White, J. A. DeShazer, C. J. Tressler, G. M. Borcher, S. Davey, A. Waninge, A. M. Parkhurst, M. J. Milanuk, E. T. Clemens,
Vocalization and physiological response of pigs during castration with or without a local anesthetic Journal of Animal Science. ,vol. 73, pp. 381- 386 ,(1995) ,
10.2527/1995.732381X