http://www.britannica.com/

http://www.wikipedia.org/

http://encarta.msn.com/

http://www.encyclopedia.com/

http://education.yahoo.com/reference/encyclopedia/

http://en.wikipedia.org/wiki/Online_encyclopedia

http://www.factmonster.com/encyclopedia.html

http://encyclopedia.jrank.org/

http://encarta.msn.com/encnet/refpages/artcenter.aspx

http://auth.grolier.com/login/go_login_page.html?bffs=N