6Levine P P, Hofstad M S. Duck disease investigation[M]. Annu Rep: New York State Vet Coll Ithaca, 1945:55-56.
7Levine P P,Fabricant J. A hitherto undescribed virus disease of duck in North Americal[J]. Cornell Vet,1950,40(4):71-86.
8Toth T E. Duck virus hepatitis[M]. Isolation and Identification of Avian Pathogens, In. Hitehner S B, Domermuth C H,Purchase H G, et al (eds.). 1975:192-196.
9Kaeberle E F. Duck viral hepatitis type Ⅰ vaccination:Monitoring of the immune response with a microneutralization test in Pekin duck embryo kidney cell culture[J]. Avian Pathol,1988, 17:325-332.
10Murty D K, Hanson I E. A modified microgel diffusion method and its application in the study of the virus of duck hcpatitis[J]. Am J Vet Rcs ,1961,22:274-278.