1. V. I. Tsaryuk, V. D. Savchenko, and V. F. Zolin, Zh. Prikl. Spektr.,56, 183–191 (1992).
2. V. K. Zakharov, I. V. Kovaleva, V. P. Kolobkov, et al., Fizika Khimiya Stekla,11, 338–348 (1985).
3. G. Blasse, G. J. Dirksen, and J. P. M. Van Vliet, Inorg. Chim. Acta,142, 165–168 (1988).
4. V. F. Zolin, V. M. Markushev, and V. I. Tsaryuk, Koord. Khimiya,11, 1209–1215 (1985).
5. M. I. Gaiduk, V. F. Zolin, V. A. Kudryashova, and V. I. Tsaryuk, Izv. Akad. Nauk SSSR, Ser. Fiz.,32, 1555–1559 (1968).