Start with a keyword search in the catalog. Once you have located a relevant item, you can look at the Subjects in the record and follow those links to find related books.
You can also refine your results by using the facets on the left side of the screen.
Examples of relevant subject headings:
To find primary resources, you can add any of the following keywords to your search: letters, diaries, speeches, newspaper articles, autobiographies, oral histories, government and organizational records, statistical data, maps, photographs, motion pictures, sound recordings, advertisements, and artifacts.