- Information in its original form when it first appears
- Information has not been published anywhere else, or put into a context, interpreted, filtered, condensed, or evaluated by anyone else.
- eyewitness accounts
- original research (the first publication of a scientific study)
- letters between two people
- a diary
- historical documents such as the US Constitution
- Information that restates, rearranges, examines, or interprets information from one or more primary sources
- newspaper or magazine articles that draw upon multiple eyewitness accounts or previous news coverage of an event
- articles reporting on a scientific study published elsewhere
- a review of a book
Remember that for many primary documents, such as Euclid's and Archimedes' writings or the letters from Thomas Jefferson to John Adams, we are not going to have the original documents. However, we may have reprints, or the documents may be included in an anthology.