Google only indexes, or searches, the "Surface Web." The surface web consists of public websites (.com, .org, .edu, .gov sites, for example), blogs, social media and news sites. Google can't search the "Deep Web." The deep web consists of websites that aren't publicly accessible, like content behind a paywall or sites only accessible with a username and password. Most academic (or scholarly) journals, which contain peer-reviewed articles, are behind a paywall. Google can't find them. The library pays for students to have access to those journals through the databases we purchase. Search the library catalog and database for peer-reviewed articles. (Google also doesn't search the "Dark Web," which are sites used for criminal activities and searchable only by a browser that hides the user's identity and location).
Is Google search biased? For more information, read these articles: