1. 1. Alexander, D. J. 1990. pp. 121-136. In: Poultry Disease. (Jordan F. T. W. ed.), Cambridge University Press, Great Britain.
2. 2. Alexander, D. J. 1991. pp. 496-519. In: Diseases of Poultry. (Calnek, B. W., Barnes, H. J., Beard, C. W., Reid, W. M. and Yoder, J. H. W. eds.), Iowa State University Press, Ames, Iowa.
3. Identification and grouping of Newcastle disease virus strains by restriction site analysis of a region from the F gene