is the online equivalent of the most current edition of the McGraw-Hill Encyclopedia of Science & Technology, which also includes biographies of scientists, recent science-related news articles, study guides, and web site links.
includes the full-text content from over 850 encyclopedias and other reference books covering a broad range of subjects. There are over 3 million articles and 200,000+ images (art, diagrams, maps and photos).
is the oldest English-language general encyclopedia still being produced. It is an excellent source for reliable and factual background information on thousands of topics, especially historical in nature.