1. Bartleby.com

Includes the Columbia Encyclopedia, Sixth Edition, dictionaries, and thesauri.

http://www.bartleby.com/

2. Britannica Concise

Featuring 28,000 short articles.

http://www.britannica.com/

3. Classic Encyclopedia

Browsable online version of the 1911 edition of the Encyclopaedia Britannica.

http://www.1911encyclopedia.org/Main_Page

4. 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

5. Encyclopedia Smithsonian

Links to on-line Smithsonian resources and answers to frequently asked questions from A to Z.

http://www.si.edu/Encyclopedia_SI/

6. HighBeam Encyclopedia

Offers articles from the Columbia Encyclopedia and Britannica Concise Encyclopedia.

http://www.encyclopedia.com/

7. How Stuff Works

Articles explain how hundreds of things work, from elements of the human body to space-age technology.

http://www.howstuffworks.com/

8. 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/

9. Information Please

Online dictionary, Columbia Encyclopedia, and almanac reference.

http://www.infoplease.com/

10. Knol

Peer-reviewed encyclopedia from Google. Articles are written by named contributors.

http://knol.google.com/k