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US Patent & Trademark Office Fulltext Patents DatabaseAnyone can use
Also Known as uspto
The Full-Text Database now offers all US patents issued since 1790, in the form of searchable patent numbers and current US classifications hyperlinked to full-page images of each page of each patent. Searchable in five-year blocks back to 1976, and in one additional block covering the years 1790-1975. [more]

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