Primary sources are produced by participants or direct observers of an event, time period, or research study. These sources may be recorded during the event or later on, by a participant reflecting upon the event. When you are unable to obtain an original source (for example, the signed Declaration of Independence), you will have to rely on copies (photocopies, microfilm, digital copies). Copies, translations, or transcriptions of a primary source still count as a primary source.
Primary sources exist for all disciplines, including the sciences, social sciences, humanities, and the arts.
Secondary sources interpret, analyze, or comment on primary sources. They are generally created by people who weren't participants or direct observers of an event, time period, or research study.
It can be difficult to determine whether a source is primary or secondary – and sometimes an item can be both at the same time. Consider the context and content. For example, newspaper articles that are factual, first-hand accounts of an event are primary sources while those that provide interpretation, analysis, or commentary are secondary. Some do both! Newspapers aren't the only type of source that can cause confusion, as shown by the Odlin letter.
Ask a librarian if you have difficulties.
Both primary and secondary sources can appear in just about any format -- books, journals, websites, original documents, etc. However, sources are rarely identified as primary or secondary within search results. Use the definitions above to help you determine which is which.
If you are looking for historical primary sources, visit our Primary Sources: Where to Find guide.
Ask a librarian for assistance if you are having trouble finding or identifying sources.
|Discipline||Primary Source||Secondary Source|
|Art||Leonardo da Vinci's Mona Lisa.||Book exploring themes in Renaissance art.|
|Biology||Polar bear hibernation research study.||Literature review comparing hibernation studies.|
|Business||Survey of consumer confidence in Alaska.||Blog post discussing the survey results.|
|Engineering||Photograph of 1964 Earthquake damage.||Analysis of building design failure in a textbook.|
|History||Trip diary of gold prospector Jane MacDonald.||Biography of women gold prospectors.|
|Literature||Toni Morrison's Beloved.||Journal article containing a critical analysis of the book.|
|Psychology||Clinical trial on Seasonal Affective Disorder (SAD) treatment.||Newspaper article describing the research study.|