1. M. Kahan, D.P. Burks, I. Burn, W.A. Schulze, in: L.M. Levinson (Ed.), Electronic Ceramics—Properties, Devices and Applications, Marcel Dekker, New York, 1988, p. 202.
2. G. Goodman, in: R.C. Buchanan (Ed.), Ceramic Materials for Electronics—Processing, Properties and Applications, Marcel Dekker, New York, 1986, p. 131.