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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 = '501') AND (category.subclass = '21') ORDER BY date ASC, patent, type

Total of 3 patents found where: Class is '501'; Subclass is '21';

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T / S Patent Date Description Patentee Category Assigned To
U 566,045 August 18, 1896 Insulator for Electrical Purposes
Protective shield of metal with non-conducting enameled coating
WHITAKER, Alfred J. P.
TREHARNE, Frederick G.
Protective Shield  
U 2,389,386 November 20, 1945 Glazed Ceramic
Compression glaze
RUSSELL, JR., Ralston
Glaze Westinghouse Electric Corp.
U 4,782,199 November 1, 1988 Insulators Having Improved Steep Wave Front Characteristics
Suspension, head treated with special glaze to strengthen cap/cement
SEIKE, Shoji
MIMA, Toshiyuki
Suspension NGK Insulators, Ltd.

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