1. Davie, T. B. (1938). J. Path. Batu., 46.
2. Hantelmann, W. (1931). Virchois Arch. path. Atat., 22, 630.
3. Hoyer, A. (1949). J. Path. Bact. 61.
4. Lumb, G., and Beautyman, W. (1952). Ibid., 64, 679. Robson, H. N., and Scott, G. B. D. (1953). Gastroenterology, 23, 74.
5. Autopsy Diagnosis atnd Technic;Saphir, 0,1951