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• Encyclopedia Britannica Online
  Search or browse through the Encyclopedia Britannica, as well as supplemental online resources.
• Encyclopedia of Astronomy and Astrophysics
  Published by the Institute of Physics; a database of over 3,000 articles commissioned by an editorial and advisory board of 800 professionals in the fields of astronomy and astrophysics.
• Encyclopedia of Optical Engineering
  This Encyclopedia contains more than 230 entries examining technological advances and perspectives from distinguished professionals around the globe-including digital image enhancement, biological modeling, biomedical spectroscopy, and ocean optics. The Encyclopedia includes nearly 2000 figures, 560 photographs, 260 tables, and 3800 equations.
• Encyclopedia Smithsonian
  Choose topics from Art to Zoology and see what the Smithsonian Institute has on the topic.
• Information Please
  Find facts and statistics searching Information Please Almanacs, a dictionary, and encyclopedia simultaneously.
• Language Dictionaries, yourDictionary.com
  An extensive index of dictionaries covering about 300 different languages.
• Oxford English Dictionary, Third Edition
  A historical dictionary of English, which shows the current meanings of words, and traces their development through time. Contains detailed etymological analysis and quotations from a wide range of English language sources from around the world.
• Webster's Collegiate Dictionary, Tenth Edition
  A popular dictionary of English, with nearly 160,000 entries.
• Webster's Third New International Dictionary, Unabridged
  A dictionary of contemporary American English, with over 450,000 entries.