1. A. YHKIND and A. CHEBOTAREV,Phys. Chem. Stekla 6 (1980) 2.
2. Idem, ibid.9 (1983) 3.
3. GAN FU-HI, HU CHAO and HE SHU-PING, in International Symposium on Glasses, Shanghai, 1988, p. 61.
4. Idem, ibid. p. 117.
5. I. IVANOVA,J. Mater. Sci. 25 (1990) 2087.