Primary Sources are used in a variety of disciplines, and the definition may vary depending on your course. Generally, a primary source is a first-hand account of an event, period, or era by an individual who participated or by someone who lived during that time. For example, a newspaper article published in the 1860s describing a Civil War battle would qualify depending on your professor's requirements. It may also be an original source; a poem could be the primary source, whereas a critical analysis of the poem would be the secondary source.
How do I cite them?
Citing primary sources guide from the Library of Congress
When searching the library catalog for primary sources, you may want to use terms like "narrative(s)", "account", "personal", "diaries." Also, if you see a subject heading that looks like: "African Americans -- Civil rights -- History -- 20th century -- Sources.", that can be a clue that the book will contain primary sources. When in doubt, ask yourself if it's an original account of something or if it's another's interpretation of that account.