8Yang L,Yoon K J,Li Y,et al.Antigenic and variations of the 15 KD nucleocapsid protein of porcine reproductive and respiratory syndrome Virus isolates[J].Archives of Virology,1999,144:525-546.
9S.fazekas de st.groth,Doris scdeidegger.Production of monoclonal antibodies:strategy and tactics[J].Journal of Immunological Methods,1980,35:1-21.
10Green R G. Distemper in the Silver Fox[J]. Pro Soc Exp Boil Med,1928,22:546-548.