4Easterday BC, Virgina S Hinshaw David , A Halvorson, et al. Influenza Disease of Poultry[ M]. Towa State University Press, Ames, IA, USA, 1997:583-605.
7Pfitzer S, Verwoerd DJ, Gerdes GH, et al. Newcastle disease and influenza A virus in wild waterfowl in South Africa[ J]. Avian Diseases, 2000, (44) : 655 -660.
8Takahashi T, Suzuki Y, Nishinaka D, et al. Duck and human pandemic influenza A viruses retain sialidase activity under low pH conditions[J]. J Biochem, 2001, 130 (2) : 279 -283.
9Hinshaw VS, Vebster RG and Turner B. The perpetuation of Orthomyxoviruses and paramyxoviruses in Canadia waterfowl, Can[ J]. J Microbio, 1980, 126 : 622 - 629.
10Alexander DJ. A review of avian avian influenza in different bird species[J]. Vet Microbio, 2000, 74(1) : 3 -13.
