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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 = '439') AND (category.subclass = '521') ORDER BY date ASC, patent, type

Total of 1 patents found where: Class is '439'; Subclass is '521';

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T / S Patent Date Description Patentee Category Assigned To
 1912
U 1,043,321 November 5, 1912 Combined Insulator and Current Distributor
Miscellaneous style with attachment for multiple current distributors (see 1,085,813)		 KNUTZ, Ernest H.
 Miscellaneous  

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