1. 1D. J. Green ; unpublished research.
2. Chemical Strengthening of Polycrystalline Alumina
3. Strengthening Sapphire by Compressive Surface Layers
4. 5K. Matsuno , "Mechanical Strength of the Glass Substrate to Be Used as Disk Drive (Chemical Tempering)" presented at the Glass Division Meeting of the American Ceramic Society, Bedford, PA, Oct. 1, 1987 (Paper No. 25G-87F).