1. (1) Beveridge, W. I. B., and F. M. Burnet: The cultivation of viruses and rickettsiae in the chick embryo. Spec. Rep. Series Med. Res. Counc., London, No. 256, 1946.
2. (2) Bosworth, T. J., and R. E. Glover: Some observation on the nature of certain disease of sheep. Proc. Forty-ninth Ann. Cong. Nat. Vet. Med. Ass. Great Britain and Ireland, 1931. [Cit. by Tunnicliff, E. A.: Amer. J. Vet. Res., 10, 240-249 (1949) ] .
3. (3) Boughton, I. B., and W. T. Hardy: Contagious ecthyma (sore mouth) of sheep and goats. J. Amer. Vet. Med. Ass., 85, 150-178, 1934.
4. (4) Glover, R. E.: Contagious pustular dermatitis of sheep. J. Comp. Path. and Therp., 41, 318-340, 1928.
5. (5) Howarth, J. A.: Infectious pustular dermatitis of sheep and goats. J. Amer. Vet. Med. Ass., 75, 741-760, 1929.