1. Purchase, H.G. and Payne, L.N. In: Diseases of Poultry (Eds. M.S. Hofstad, H.J. Barnes, B.W. Calnek, W.M. Reid and H.W. Yoder, Jr.), Iowa State University Press, Ames, 1984, pp. 360–405.
2. Peterson, R.D.A., Purchase, H.G., Burmester, B.R., Cooper, M.D. and Good, R.A. J. Natl. Cancer Inst. 36: 585–595, 1966.
3. Cooper, M.D., Payne, L.N., Dent, P.B., Burmester, B.R. and Good, R.A. J. Natl. Cancer Inst. 41: 373–389, 1968.
4. Purchase, H.G. and Gilmour, D.G. J. Natl. Cancer Inst. 55: 851–855, 1975.
5. Witter, R.L. In: Diseases of Poultry (Eds. M.S. Hofstad, H.J. Barnes, B.W. Calnek, W.M. Reid and H.W. Yoder, Jr.), Iowa State University Press, Ames, 1984, pp. 406–417.