Primary sources are first-hand accounts, written or recorded by people with direct experience and knowledge from the period being studied. Examples of primary sources include a diary written by someone during the period or who witnessed the event, photographs or video of an event, or newspaper articles written by people who directly witnessed an event.
Many library research guides have a specific section on primary sources, such as the following:
For other guides do a keyword search with the phrase "primary sources".
Search OneSearch for primary sources. Use subject keywords for your topic and words like "diaries," "personal narratives" or "interviews," e.g. Spain and civil war and diaries
Search the Manuscript Collections of Fondren Library's Woodson Research Center. These collections include source material such as diaries, letters, photographs, drafts of literary and scientific works, audio and video recordings, legal documents, and much more.
Geisel Productions Web Series defines primary (versus secondary) sources of information. UCSD Social Sciences & Humanities Library [3:01 minutes].