1. Benson, L., and Goddard, J. (1954). Amer. Rev. Tuberc., 69, 595.
2. Houston, J., Harkness, J., and Whittington, R. B. (1945). Acta tuberc. scand., 19, 153.
3. Lawrence, J. S. (1950). J. clin. Path., 3, 332.
4. Mann, F. D. (1948). Amer. J. clin. Path.. 18, 79.
5. Miller, A. K., and Whittington, R. B. (1942). Lancet, 2, 510.