Britannica Online Academic Edition combines the complete Encyclopedia Britannica and full-text articles from various periodicals with select Web sites, multimedia tools, and a host of reference tools including the Merriam-Webster's Collegiate Dictionary and Thesaurus.

Columbia Encyclopedia (6th ed., 2007) contains more than 57,000 articles. It is available through infoplease.com. 

Funk & Wagnalls New World Encyclopedia offers over 25,000 encyclopedic entries covering a variety of subject areas. It is updated annually.