This is the 6th edition by Columbia University Press, 2001-2004. Containing nearly 51,000 entries and more than 80,000 hypertext cross-references
Columbia Encyclopedia, Sixth Edition, 2001-2004.
"The most up-to-date encyclopedia available on the web" by Bartleby. Contains neary 51,000entries. See: "How to Use the Columbia Encyclopedia" by Fact Monster at http://www.factmonster.com/encyclopedia/ce6howto.html