Consider using a combination of the following as keywords in your search:
Primary sources are first-hand accounts, original data, or records created at the time of an event. They may be adapted into digitized versions, but they are still considered primary sources. Primary sources can be any format, including letters, diary entries, official records, and other written texts, interviews, artworks, films, and photographs.
For more information, please view the MHC Library Services video tutorials: