1. For reviews, see: C.J.Brinker and G.W.Scherer, Sol-Gel Science, the Physics and Chemistry of Sol-Gel Processing (Academic Press: San Diego, 1990)
2. D.R.Ulrich, J. Non-Cryst. Solids 121, 465 (1990)
3. H.Schmidt, B.Sieferling, G.Philip, and K.Deichmann, in Ultrastructure Processing of Advanced Ceramics; edited by J.D.Mackenzie and D.R.Ulrich (John Wiley, New York, 1988), p. 651
4. H.Schmidt, J. Non-Cryst. Solids 112, 419 (1989)
5. G.L.Wilkes, H.Huang, and R.H.Glaser, in Silicon-Based Polymer Science (Advanced in Chemistry Series 224), edited by J.M.Ziegler and F.W.Fearon (Am. Chem. Soc., Washington, DC, 1990), p. 207