8Cho J G, Dee S A. Porcine reproductive and respiratory syndrome virus[ J]. Theriogenology, 2006, 66 (3) : 655 -662.
9Neumann E J, Kliebenstein JB, Johnson CD, et al. Assessment of the economic impact of porcine reproductive and respiratory syndrome on swine production in the United States[ J ]. Am Vet Med Assoe, 2005, 227:385 -392.
10Tian K, Yu X, Zhao T, et al. Emergence of Fatal PRRSV Variants: Unparalleled Outbreaks of Atypical PRRS in China and Molecular Dissection of the Unique Hallmark[ OL]. PLOS One, 2007, (2) :526.