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SELECT DISTINCT patent.*, YEAR(date) as year FROM patent LEFT JOIN category ON category.patent = patent.patent AND category.type = patent.type WHERE (category.class = '438') ORDER BY date ASC, patent, type

Total of 1 patents found where: Class is '438';

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T / S Patent Date Description Patentee Category Assigned To
 1972
U 3,658,583 April 25, 1972 Method for Producing Semi-Conducting Glaze Compositions for Electric Insulators
RFI semi-conductive glaze formulas		 OGAWA, Yutaka
 RFI NGK Insulators, Ltd.

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