1. W. Spaan, D. Cavanagh, and M.C. Horzinek. In: “Immunochemistry of viruses, II. The basis for serodiagnosis and vaccines”. M.H.V. van Regenmortel and A.R. Neurath, eds., p. 359, Elsevier, New York (1990).
2. K.V. Holmes. In: “Virology, 2nd edn.”, B.N. Fields, D.M. Knipe et al., eds., p. 841, Raven Press, New York (1990).
3. H. Wege, S. Siddell, and V. ter Meulen. Curr. Top. Microbiol. Immunol. 99: 165 (1982).
4. M.M.C. Lai. Annu. Rev. Microbiol. 44: 303 (1990).
5. B.G. Hogue, B. King, and D.A. Brian. J. Virol. 51: 384 (1984).