- USPTO http://www.uspto.gov/
- US Published Application Full-Text Database Number Search
- Free Patents On-Line http://www.freepatentsonline.com/
- Glossary of terms used on the USPTO www.uspto.gov/main/glossary
- CIPO (Canadian Intellectual Property Office) http://strategis.ic.gc.ca/sc_mrksv/cipo/welcome/welcom-e.html
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- Patents Storm http://www.patentstorm.us/