http://scholar.google.com/

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http://vivisimo.com/

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http://www.copernic.com/index.html

http://dmoz.org/

http://infomine.ucr.edu/

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http://www.loc.gov/

http://www.daypop.com/

http://www.quotationspage.com/

http://www.wipo.int/ipdl/en/


http://www.cortland.edu/history/research.html

http://digicoll.library.wisc.edu/HistResEur/

http://www.metacrawler.com/

http://www.ask.com/