Primary sources offer an eyewitness view of a particular event.
A primary source is a document or other sort of evidence written or created during the time of study.
Primary documents include diaries OR speeches OR letters OR minutes OR interviews OR journals OR narratives OR memoirs OR images OR news film footage OR autobiographies OR official records OR photographs. (You can copy this list and paste it into one of your search box lines...)
WorldCat can provide primary sources.
Image source: Iron shackles used in slave trade. Chicago Historical Society. #F003 as shown on slaveryimages.org, compiled by Jeromy Handler and Michael Tuite and sponsored by the Virginia Foundation for the Humanities and the University of Virginia Library.