1. Doyle, T.M. J. comp. path. 40: 144–169, 1927.
2. McFerran, J.B. and McCracken, R.M. In: Newcastle Disease, (Ed Alexander, D.J.) Martinus Nijhoff, Boston, 1988.
3. Kaleta, E.F and Baldauf, C. In: Newcastle Disease. (Ed Alexander, D.J.) Martinus Nijhoff, Boston, 1988.
4. Beard, C.W. and Hanson, R.P. In: Diseases of Poultry. (Ed Hofstad, M.S.) Iowa State University Press, Ames, 1981.
5. Alexander, D.J. and Allan, W.H. Avian Path. 3: 269–278, 1973.