Firsthand Accounts or Written at the Time of the Event?
Authenticity of the source itself
What is the Point of View?
Compare the multiple pieces of evidence, or accounts of one event provided by different primary sources, in order to evaluate the reliability of each document.
For more information,
Library of Congress Using Primary Sources. http://www.loc.gov/teachers/usingprimarysources
National Archives of the United States. Document Analysis Worksheets https://www.archives.gov/education/lessons/worksheets/