The sites below offer collections of open access textbooks for multiple subject areas. Most content is free; some sites require registration. Check with your professor before you use an open access textbook for your course work.
NOTE: If you are looking for a textbook for an LSB internship, you have a couple of options:
Tip: Be willing to spend some time exploring these textbook sites. You may have to search within an e-textbook collection or click through a few pages on the website to get to a textbook that will help with your assignment.