1. Boorman, K. E., Dodd, B. E., and Mollison, P. L. (1942). Brit. med. J., 2, 535.
2. Chown, B. (1944). Amer. J. clin. Path, 14, Tech. Sect., 8, 114.
3. Chown, B. and Lewis, M. (1946). Canad. med. Ass. J., 55, 66.
4. Diamond, L. K., and Abelson, N. M. (1945). J. Lab. clin. Med., 30, 204.
5. Discombe, G., and Meyer, H. (1948). J. clin. Path, 1, 73.