» HighBeam Encyclopedia
   Free resource offers more than 50,000 concise articles from the Columbia Encyclopedia.
   http://www.encyclopedia.com/

» 1911 Encyclopedia Britannica
   Offers the 11th Edition Encyclopedia Britannica which is now in the public domain. All articles are searchable and alphabetized.
   http://encyclopedia.jrank.org/

» Bartleby.com
   Includes the Columbia Encyclopedia, Sixth Edition, dictionaries, thesauri, and more.
   http://www.bartleby.com/

» Britannica Concise
   Featuring 28,000 short articles.
   http://concise.britannica.com/

» Encyberpedia
   Electronic encyclopedia with its own content as well as over 10,000 links to the best reference sites on the Internet.
   http://www.encyberpedia.com/cyberlinks/links/index.html

» Encyclopaedia Britannica Online
   Provides complete text of Encyclopaedia Britannica with search capabilities, related links, and multimedia enhancements. Full text for subscribers only; free trial available.
   http://www.britannica.com/

» Encyclopedia Smithsonian
   Links to on-line Smithsonian resources and answers to frequently asked questions from A to Z.
   http://www.si.edu/Encyclopedia_SI/start.htm

» How Stuff Works
   Articles explain how hundreds of things work, from elements of the human body to space-age technology.
   http://www.howstuffworks.com/

» Hutchinson Encyclopedia
   "A subset of the content (concise set) is provided for free, the access to the rest of the Hutchinson Encyclopedia requires subscription."
   http://encyclopedia.farlex.com/

» Information Please
   On-Line dictionary, Internet encyclopedia, and almanac reference.
   http://www.infoplease.com/

» MSN Encarta Encyclopedia
   Online home of the Encarta encyclopedia, world atlas, dictionary, thesaurus, multimedia collection, and homework tools.
   http://encarta.msn.com/

» Nuttall Encyclopædia of General Knowledge
   Approximately 14,000 entries on topics including art, geography, literature, philosophy, religion. Originally published in 1907.
   http://www.fromoldbooks.org/Wood-NuttallEncyclopaedia/

» Simple English Wikipedia
   User-contributed online encyclopedia intended for people whose first language is not English.
   http://simple.wikipedia.org/

» The LoveToKnow Free Online Encyclopedia
   Browsable. Based on the eleventh edition of the Encyclopedia Britannica, first published in 1911.
   http://www.1911encyclopedia.org/

» The Probert Encyclopaedia
   Reference source with several hypertext linked entries covering a broad variety of subjects.
   http://www.probert-encyclopaedia.co.uk/

» Wikinfo
   User edited encyclopedia based on Wiki software. Contains articles, information on editing, and a list of differences between this encyclopedia and Wikipedia.
   http://www.wikinfo.org/

» Wikipedia
   A free encyclopedia built collaboratively using Wiki software. (GNU Free Documentation License) and with over 1,000,000 articles. Note that because articles can be "vandalized," information on Wikipedia is not always accurate.
   http://en.wikipedia.org/wiki/Main_Page

» World Book Encyclopedia
   Online version of the complete reference work along with dictionary, atlas, links, magazines, historical documents, audio, video, images, and 3D photographs. Requires free temporary registration with option to buy continued access for full articles.
   http://www.worldbook.com/