One way to identify books that are primary sources is to look for books written by people who were involved in the event or activity you are researching. When you look at secondary sources, write down the names of people and then look for them as authors.
In the UW Libraries Catalog, books that have been assigned subject heading could be primary sources. Use the library catalog "Subject" search to locate items. Consider using some of the following subheadings in a search.
--Diaries
--Correspondence
--Biography
--Sources
--Anecdotes
--Personal narratives
--Interviews
Examples:
Fighter Pilots -- United States -- Biography
Soldiers -- Alabama -- Correspondence
War Correspondents -- United States -- Interviews
African American Sailors -- Diaries
Vietnam War, 1961-1975 -- Personal Narratives, American
United States. Army. Women's Army Corps -- Biography
World War, 1939-1945 -- Cryptography -- History -- Sources
For information about the difference between primary and secondary sources, refer to this guide.