1. J. Daniels, R. Wernicke, Philips Research Rept., Vol. 31, No. 6, Research Laboratory of N.B. Philips, Netherlands, 1976, pp. 489–559.
2. Barium titanate as semiconductors with blocking layers;Heywang;Solid-State Electron.,1961
3. G.H. Jonker, Advances in Ceramics, Vol. 1, The American Ceramic Soc., Ohio, 1981, pp. 155.
4. PTCR effect in BaTiO3;Lewis;J. Am. Ceram. Soc.,1985
5. E.D. Macklen, Thermistors, Electrochemical Publications, 1979, pp. 188–217.