Primary sources can take many forms. Some examples:
Consult with your instructor if you're not sure what constitutes a primary source for your project. You can also consult this guide on primary sources.
Try adding the word study if you're searching from the libraries' website. Many databases allow you to limit your results to the source type Studies or Empirical Studies. Try searching for a topic and using this limiter in your search.
"A literature review surveys books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have explored while researching a particular topic and to demonstrate to your readers how your research fits within a larger field of study." (Source)
Try a starting search for your topic in the main search box on the libraries' home page. Once you have some search results, use the "Material Type" limit on the left-hand side to limit to Books - then click on a title.
Note the call number, or book's location, at the bottom of the page. Try going to this call number in the book stacks of whatever library is indicated, and take a look at the books NEAR that book to discover some other angles on the same topic.