The libraries' have the DSM-5 in both print and online. The print copies are on reserve at the main circulation desk at Lied Library.
To access the online version of the DSM-5 (and older versions as well), please go to PsychiatryOnline either through the libraries' website or by using this link: http://ezproxy.library.unlv.edu/login?url=http://www.psychiatryonline.com/
If you are off campus, you will be asked login with either your ACE account and password or your library barcode and PIN.
Once you are on the site, go to the navigation at the top and look for DSM Library (see image below) The current and older manuals are available full text here.