Moraes, Aury Nunes de, et al. “Epidural Administration of Ropivacaine or Ropivacaine and Xylazine in Cattle”. Semina: Ciências Agrárias, vol. 35, no. 4Supl, Sept. 2014, pp. 2481-90, doi:10.5433/1679-0359.2014v35n4Suplp2481.