Credo Reference: permits simultaneous full text search of hundreds of dictionaries and encyclopedias in the humanities, social sciences, and sciences.
Gale Virtual Reference Library: permits simultaneous full text search of hundreds of dictionaries and encyclopedias. Emphasis is on Liberal Arts.
Access Science: Online encyclopedia of science and technology. (Corresponds to the print version, McGraw-Hill Encyclopedia of Science & Technology).
Oxford Reference Online: Oxford Reference is Oxford's general reference service with access to many Oxford dictionaries and handbooks.