1. J. N. Weber, Spectrochlmica Acta,16, no. 11, 1960.
2. G. Graue, W. Lückerath, and R. Marotz, Chem. Ingr, Techn.,34, no. 4, 300, 1962.
3. V. D. Ivanova and L. I. Topalov, Zav. lab.,30, 136, 1964.
4. N. K. Rudnevskii and G. I. Golitsin, Izv. AN SSSR, ser. fiz.,19, no. 1, 123, 1955.
5. N. K. Rudnevskii and u. S. Kalinin, in: Papers on Chemistry and Chemical Engineering, vol. 1 [in Russian], Gor'kii, 7, 1958.