Entries in subject encyclopedias are not acceptable as sources in your final research paper, so why use them? The main reason is because subject encyclopedias are invaluable starting points in the research process:
An investment of thirty minutes of your time with subject encyclopedias thus can save you hours of digging or flailing about in the information universe!
If you are interested in a specific technology, the Groundbreaking Scientific Experiments, Inventions and Discoveries series can be an excellent starting point!
The following links will take you to large digital collections of subject encyclopedias. The Gale Virtual Reference Library is an especially good place to start for STS courses, as it includes the Mcgraw-Hill Dictionary of Science & Technology and the Dictionary of Scientific Biography.
You'll find these print sources in the reference section on the main floor or in the main stacks! As you use these and other reference sources, keep these tips in mind: