Lexico Publishing Group provide an English dictionary and On This Day, with additional reference material from Crystal Reference, The Columbia Encyclopedia, and Wikipedia. Web ...
http://www.reference.com/

Search online reference materials - American Heritage Dictionary, Columbia Encyclopedia, Roget's Thesaurus, World Factbook, Spanish to English Dictionary, Quotations, Shakespeare s ...
http://education.yahoo.com/reference/

Online English dictionary, thesaurus and reference guide. Includes word games, online translator, and word of the day feature.
http://dictionary.reference.com/

noun . 1. an act or instance of referring. 2. a mention; allusion. 3. something for which a name or designation stands; denotation. 4. a direction in a book or writing to some ...
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In general, a reference is a relation between objects in which one object designates by linking to another object. Such relations as these may occur in a variety of domains ...
http://en.wikipedia.org/wiki/Reference