1. P.K. Davies, in Materials and Processes for Wireless Communications, ed. T. Negas and H. Ling, Ceramic Transactions 53, p. 137, American Ceramic Society, Westerville, OH (1995).
2. T. Negas, G. Yeager, S. Bell, and R. Amren, in Chemistry of Electronic Ceramic Materials, ed. P.K. Davies and R.S. Roth, NIST Special Publication 804, p. 21 (1990).
3. R.S. Roth, unpublished.