Keep in mind that for your particular course(s), your professor would like you to stick to using books published at a University press or approved press ONLY. This means that the books will have gone through a rigorous editing process that includes peer review.
Not sure how to figure out where a book was published? If you have the book in your hands, it should be somewhere on the cover or in the first few pages of the book, usually with the copyright info. If you're looking at a book on the Library website, look in the "Details" section and you'll see a line titled "Publisher."
Below is a list of publishers/book presses approved by Dr. Langton (if your book's publisher is not on this list, but IS a university press, ask your professor if you can use it!):
Can't find the book or article you want? Try Interlibrary Loan (ILL)! We also have an ILL FAQ for more info!