1. H. Richter, Z. Physik. 44 (1944) 406.
2. J. Dixmier, K. Doi and A. Guinier, in “Physics of Noncrystalline Solids”, edited by J. A. Prins (North Holland, Amsterdam, 1965) p. 67.
3. R. C. Crewdson, Ph.D. Thesis, California Institute of Technology, Pasadena, California (1966).
4. G. S. Cargill III, (a) J. Appl. Phys. 41 (1970) 12;
5. ibid 41 (1970) 2248.