Now that you have consulted reference materials to gather names of people, places, and events, you should have the keywords needed to find primary texts using the Library Catalog.
Primary sources can also be found by browsing Databases. Review the next page of this guide for recommendations.
Use the Advanced Search under the Library Catalog tab.
Type the name of the event or person you're researching in the first search term line. In this example, we have entered "Vietnam War."
In the line below it, you can try "primary sources" as a second search term with some success, or try entering a few types of primary source documents as keywords with the OR function between each word as shown below: letters OR diaries OR correspondence.
You can expand your results by toggling from "Library Catalog" to "Articles, Books & More" at the top of the search box. This increases the quantity of results but some will be less relevant than others.
Here are some more keyword ideas: