Primary sources are first-hand accounts by participants of a particular event or materials produced at the same historical time period.
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:
Use ORs and parentheses to combine synonyms or multiple topics
(oil OR petroleum OR crude)
(antibiotic OR antiviral)
(woman OR girl OR female)
Truncate roots of important words* to find plurals and more
perform* (searches for perform, performance, performativity, etc.)
Insert a “wild card” [*?$!] to catch words with different spellings
*Truncation and wild cards work differently in different databases. Check the help section of the database to learn what symbol to use and how to properly use it.
Combine concepts with AND to find more relevant sources
picasso AND Africa
internet AND privacy
bedrock AND Massachusetts AND hydrology
Use “double quotes” to find exact phrases
Use proximity searching* to find words near each other
women NEAR violence
progressive NEAR/10 tax
"global warming" NEAR/20 "sea level"
*Proximity searching works differently in different databases. Check the help section of the database to learn how to properly use it.