1. Lenher, V., and Merrill, H. B., J. Amer. Chem. Soc., 39, 2630 (1917).
2. Titus, A. C., J. Indust. Hyg. Toxic., 19, 138 (1937).
3. King, E. J., and McGeorge, M., Biochem. J., 32, 417 (1938).
4. Briscoe, H. V. A., Matthews, J. W., Holt, P. F., and Sanderson, P. M., Trans. Inst. Min. Met., 46, 270, 291 (1937).
5. Whitehouse, A. G. R., J. Indust. Hyg. Toxic., 20, 556 (1938).