1. http://en.wikipedia.org/wiki/Varistor
2. Varistor ceramics;Clarke;Journal of the American Ceramic Society,1999
3. Nonohmic properties of zinc oxide ceramics;Matsuoka;Japanese Journal of Applied Physics,1971
4. Zinc oxide varistors-a review;Levinson;American Ceramic Society Bulletin,1986
5. Grain boundary properties in ZnO varistors;Einzinge;Advances in Ceramics,1981