Internet Archive
You can sometimes read books still under copyright online using the Internet Archive Open Library. These books cannot be downloaded but can be viewed on screen for one hour with a free Internet Archive account. The controlled digital lending model only allows one person to read each print copy owned by the Open Library at a time, so if the book you want can't be borrowed because it is in use, search to see if there's another scanned copy on the site. Some publishers may require you to use Adobe Digital Editions instead of your browser to view a borrowed book.
UNLV Libraries subscriptions
Items with red UNLV icons will require your ACE login for off-campus access. These are behind a paywall and the publishers or distributors rely on libraries and universities to pay for access for students and faculty.
Hathi Trust
The Hathi Trust has access to books and periodicals in the public domain (printed before 1928 or by the U.S. Government). No login is required to read them onscreen, but if you want to download a PDF of the whole book, log in by selecting UNLV from the institutional access drop-down menu and you'll be redirected to use your ACE account.