• United States Patent
  • European patent office

  • German Patent and Trade Mark office

  • Delphoin Intellectual Property Network

  • Intellectual Property Digital library

  • Strategis.gc.ca : Canada's Business and consumer site

  • Danish Patent and Trade Mark office

  • Japan Patent office

  • Patent office of Republic of Bulgaria

  • The UK Patent office
  • Rocket Search IBM
  • MicroPatent
  • PatentExplorer.com
  • CAS : A Division of the American Chemical society
  • Yet 2.com