1. H. Gerding and J. W. Maarsen, Rec. Trav. Chim.,76, 481 (1957).
2. C. Christol and H. Christol, J. Chim. Phys. Chim.-Phys. Biol.,62, 246 (1965).
3. E. Steger and M. Kuntze, Spectrochim. Acta,23A, 2189 (1967).
4. A. N. Pudovik, I. Ya. Kuramshin, A. B. Remizov, A. A. Muratova, and R. A. Manapov, Zh. Obshch. Khim.,44, 44 (1974); A. I. Fishman and A. B. Remizov, Opt. Spektrosk.,38, 858 (1975).
5. R. R. Shagidullin, I. I. Vandyukova, and I. A. Nuretdinov, Izv. Akad. Nauk SSSR, Ser. Khim., 801 (1976).