Derwent Innovations Index (DII), 1963-presentFacilitates precise patent searching, letting you conduct patent and citation searches of inventions in chemical, electrical, electronic, and mechanical engineering. Also merges value-added patent information with patent citation information.
SciencDirect has a "References" field that can be proximity searched to find patent numbers, inventors, and title words
Science Citation Index Expanded (Web of Science)A multidisciplinary index covering the journal literature of the sciences. It indexes more than 5,700 major journals across 164 scientific disciplines. The best database for finding what papers have cited other papers. Cited references can be traced forward in time.