Whether you are in the process of revising your literature review, or just starting to pull together relevant research papers, it is worth taking a step back and considering what exactly you are trying to accomplish in writing the introduction, or literature review for your thesis, and what we mean we talk about "the literature".
A literature review (or lit review, for short) is an in-depth critical analysis of published scholarly research related to a specific topic. Published scholarly research (the "literature") may include journal articles, books, book chapters, dissertations and thesis, or conference proceedings. In your case, your lit review will seek to examine existing research, gaps in understanding, and theoretical underpinnings, to situate your work within a body of scientific knowledge. A well formed lit review is not only imperative for understanding your topic thoroughly and developing your research, but is one way in which you will participate in an ever-evolving scholarly conversation with past, present, and future research.
Many of our databases have this 
button or this 
button, which searches for the full-text of the article in our collections. If we don't have it electronically, look for the "Request article scan" link in the "Get It" section.
Don't pay for articles you find in Google Scholar. Learn how to connect Google Scholar to the library's holdings.