1. Crandall, H. W., J. Chem. Phys., 17, 603 (1949).
2. Betts, R. H., and Michels R. K., J. Chem. Soc., S 286 (1949).
3. Robinson, R. A. (private communication).
4. Jander, G., and Wendt, H., Z. anorg. Chem., 258, 1 (1949).
5. Hoard, J. L., and Stroupe, J. D., quoted in “Spectroscopic Properties of Uranium Compounds”, by G. H. Dieke and A. B. F. Duncan (McGraw-Hill, New York, 1949).