Other Virtual Reference Collections
Gale Virtual Reference Library 
A database of encyclopedias, almanacs, and specialized reference sources for multidisciplinary research.
Bartleby.com (Great Books Online)
Perhaps the best free reference site on the Internet--it's got
everything, from Bartlett's Quotations to the King James Bible, all
in searchable formats. A must!
Internet Library
for Librarians: Ready Reference
Includes almanacs/fact books, bibliographies, biographies,
directories, dictionaries/thesauri, encyclopedias, maps/travel,
news/weather, miscellaneous.
Internet Public
Library: Reference
Annotated selection of authoritative resources.
Martindale's The Reference Desk
Strong on sciences and health.
Michigan eLibrary (MeL) Reference Desk
Comprehensive site.
Quick Reference (Purdue University Libraries)
Includes international dictionaries, maps, currency exchange rates, and science data.
Quick Reference (University of California, Irvine)
Includes encyclopedias, tables and calculators.refdesk.com
Fast access, easy navigation, and comprehensive content.
Reference Shelf (University
of California, San Diego)
A plethora of information resources.
Virtual Reference
Shelf
Selected Web resources compiled by the Library of Congress.