OneSearch on the PO Library website, as well as most library databases, allows you to limit results to peer-reviewed journals only. In OneSearch you can use the filter on the left after you perform a search:
You can also start your search using the Peer Reviewed tab in One Search.
In almost any library database, you can also check the "Limit to Peer Reviewed" box, usually found under the main search box. Here's an example in ProQuest PsycINFO:
Another option if you want to confirm a journal is peer-reviewed is to search the 
Ulrichsweb periodicals directory for the title of the journal. If you see this icon, the journal is refereed (peer-reviewed). You can find Ulrichsweb in the library under Databases A-Z.
Google Scholar is the easiest way to find scholarly and peer-reviewed literature on the web.
Google Scholar is a search engine that provides links to full-text articles to which the University Library System subscribes or to articles made freely available by the publisher. Google Scholar also provides articles from academic publishers, professional societies, preprint repositories, and scholarly articles posted on the web. In addition, many articles are available full text when connected to the PO Library (from the Guide to Searching for Library Resources). Finally, Google Scholar provides citations along with abstracts of the article if it is protected by copyright.
For more information, including instructions on how to link Google Scholar to the TCS Education System Libraries (which includes Pacific Oaks Library) visit the Google Scholar page from the Guide to Searching for Library Resources.