1. CAROZZI, L., Occupation and Healh, Vol. DORE, S. E., Brit. J. Derm. Syph. (Igog).
2. , I.L.O., Geneva (1933).
3. HENRY, S. A., & HORNER, S. G., Brit. Encyclopaedia Med. Practice (1939). 11, i6i.
4. JACOBSON, J. J., S. African Med. J. (1934). 8, 408.
5. JAMES, W. D., Quart. Med. J., Yorks. (1896). 4, I5I. JONES, JONES, A. J.