From the U.S. Patent and Trademark Office:
Cooperative Patent Classification (CPC) --- the classification system used for advanced subject searching:
Other important websites for accessing patents and patent information:
Video from the United States Patent and Trademark Office (USPTO)
Guide for preliminary patentability searching of the documents of the United States Patent Office.
Tutorial from the University of Minnesota Libaries
The European Patent Office (EPO) and the United States Patent and Trademark Office (USPTO) have jointly prepared CPC training material to support users in their learning process of the CPC classification system.
Help in understanding the parts of a U.S. patent.
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