*Classification Numbers can be found [http://www.uspto.gov/web/patents/classification/selectnumwithtitle.htm here].
*USPTO's new visual database, PatentsView, can be found [http://www.patentsview.org/web/ here].
*[https://www.google.com/googlebooks/uspto-patents-pair.html#AvailableApplications USPTO PAIR (Patent Application Information Retrieval)] *Google's helpful article on downloading USPTO PAIR (Patent Application Information Retrieval) data can be found [https://www.google.com/googlebooks/uspto-patents-pair.html#AvailableApplications here].