1. Clark, C. H. W. and Steatite & Porcelain Products Ltd., England; “Insulators having semiconductive layers to increase the capacitance thereof,” U.S. Pat. 3,243,505; March 29, 1966.
2. International Electrotechnical Commission, Document: 36 (Secretariat) 37 of June 1969, Technical Committee No. 36: Insulators, CISPR Publication 1A dated 1966.