During the Roy O. renovation, none of those books are available. Books housed in the Prevo Science Library and the Music Library are still available, and the stacks are reopened this year.
You can limit your search to e-books that DePauw owns, by checking those two filters on the left side.
Or you can leave your search to show all books. When you see a book that DePauw doesn't own, click on the blue "Request Item" button to get the book, most likely a print copy through interlibrary loan. This will take a few days.