GIO is a free online information service supported by nearly twenty public, state and academic libraries throughout the United States. All participants are designated Federal depository libraries in the U.S. Government Publishing Office's Federal Depository Library Program.
The Library serves as the research arm of Congress and is recognized as the national library of the United States. Its collections comprise the world's most comprehensive record of human creativity and knowledge.
Slug Books is a site where students can search for inexpensive textbooks. You can compare prices and also sell your current text books.