Written by 
Primary Sources
- Original materials that provide direct evidence or first-hand testimony concerning a topic or event.
- Contemporary sources created at the time when the event occurred (e.g., letters and newspaper articles–as long as the writer is a first-hand witness) or later (e.g., memoirs and oral history interviews).
- Primary sources may be published or unpublished. Unpublished sources are unique materials (e.g., family papers) often referred to as archives and manuscripts.
- Primary sources vary by discipline. How the researcher uses the source generally determines whether it is a primary source or not.
Secondary Sources
- Works that interpret, analyze, and discuss the evidence provided by primary sources (e.g., scholarly books and articles).
- Secondary sources are generally a second-hand account or observation at least one step removed from the event.
- Secondary sources can be considered to be primary sources depending on the context of their use. For example, Ken Burns’ documentary of the Civil War is a secondary source for Civil War researchers, but a primary source for those studying documentary filmmaking.
Tertiary Sources
- Books or articles that synthesize or distill primary and secondary sources–for example dictionaries, encyclopedias, indexes, and textbooks. (Sometimes these are lumped in with the secondary sources category.)
- Keep in mind that a secondary or tertiary source can lead you to a primary source by either referencing it, including it in a footnote or reproducing it in its entirety. For example, at first glance, a source like “World War I: Encyclopedia” would not seem to be a primary source but if you look at the contents, volume five of this encyclopedia is entirely devoted to transcripts of documents of the war. Many subject encyclopedias like this one will turn out to be a rich source of primary source materials.
The Historian researching World War I might utilize:
- Primary Sources: Newspaper articles, weekly/monthly news magazines, diaries, correspondence, and diplomatic records from the time period.
- Secondary Sources: Articles in scholarly journals analyzing the war, possibly footnoting primary documents; books analyzing the war.
The Literary Critic researching literature written during World War I might utilize:
- Primary Sources: Novels, poems, plays, diaries, and correspondence of the time period.
- Secondary Sources: Published articles in scholarly journals providing analysis and criticism of the literature; books analyzing the literature; formal biographies of writers from the era.
The Psychologist researching trench warfare and post-traumatic stress disorder in World War I veterans might utilize:
- Primary Sources: Original research reports on the topic or research notes taken by a clinical psychologist working with World War I veterans.
- Secondary Sources: Articles in scholarly publications synthesizing results of original research; books analyzing results of original research.
The Scientist researching long term medical effects of chemical warfare on exposed veterans might utilize:
- Primary Sources: Published articles in scholarly journals reporting on a medical research study and its methodology.
- Secondary Sources: Published articles in scholarly journals analyzing results of an original research study; books doing the same.
View our LibGuide that explains primary sources in more detail and provides access to many primary source repositories.