1. Rouxel, J., Ann. Chim., Paris, 7, Ser. 13, 49 (1962).
2. Hagenmuller, P., Rouxel, J., David, J., and Colin, A., C.R. Acad. Sci., Paris, 252, 282 (1961); 253, 667 (1961).
3. Schafer, H., Wittig, F. E., and Wilborn, W., Z. Anorg. Allgem. Chem., 297, 48 (1958).
4. Lyu, Sub Y., and Zvyagintsev, O. E., Zhur. Prik. Khim., 33, 1208 (1960).
5. Schober, R., and Thilo, E., Ber., 73B, 1219 (1940).