These are full-text books online, and you can access them off campus with your EUID/password. Check your account status/reset password at ams.unt.edu Some e-books enable only one user to view the book at a time, and some allow multiple users. You can find e-books in the Discover Library Catalog (you can limit to Online) in the access filter to the left of your search box.
You click on Other Searches Tab, then scroll to "Cataloged Books and More" option.
Access UNT Libraries: No library card needed! Just use your UNT I.D. card to check out materials in person at UNT Libraries, and EUID and Password for UNT online items.