The phrase "primary sources" means different things in different disciplines. In many natural and physical sciences, it means studies that tell about original research projects. Looking for peer-reviewed sources will be your best bet.
In history and other fields, this refers to things published or produced during the time that something was happening, or in the words of someone who lived through a time or event. Common types of primary sources are:
- newspapers
- diaries
- photographs
- memoirs/autobiographies
- oral histories
We have a number of databases that are all/mostly primary source materials - check this list for ideas. Additionally, this list highlights our newspaper databases.
Finally - check this LibGuide on Finding Primary Sources.