1. Zachariasen, W. H., J. Amer. Chem. Soc., 54, 3841 (1932).
2. Warren, B. E., J. Amer. Chem. Soc., 17, 249 (1934).
3. Carraro, G., et al., Physics of Non-Crystalline Solids (Proceedings of the International Congference, Delft, July 1964) (North-Holland Ablishing Company, Amsterdam, 1964).
4. Warren, B. E., J. App. Phys., 8, 645 (1937).
5. Tilton, L. W., J. Res. Nat. Bur. Stand., 59, 139 (1957).