Primary sources are first-hand accounts by participants of a particular event or materials produced at the same historical time period. Secondary sources are books and articles written by scholars investigating a research topic using primary sources.
If you were examining racism in the 1911 edition of the Encyclopaedia Britannica , the article in the encyclopedia on the "Negro" would be a primary source. However, an article in the American Historical Review analyzing racism in the Britannica would be a secondary source . (Richard Marius, A Short Guide to Writing About History , pp. 14-15.)
Some examples of primary sources include: