1. Benjamin, B. (1953). Brit. J. Tuberc., 47, 4.
2. Daniels, M., Ridehalgh, F., Springett, V. H., and Hall, L. M. (1948).
3. Tuberculosis in Young Adults". Report on the Prophit Tuberculosis Survey 1935-1944;Lewis, London
4. Downes, J. (1935). Amer. J. Hyg., 22, 731
5. Grenvllle-Mathers, R., and Trenchard, H. J. (1953). Proc. roy. Soc. Med., 46, 809.