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Primary and Secondary Sources


When doing research, it is helpful to determine the type of sources that are needed. Sources typically fall into three categories, namely, primary sources, secondary sources, and tertiary sources. Each of these categories is dependent upon the subject discipline and field of study. Read the definitions provided to learn about each source, and see the table of examples differentiating Art, Humanities, Social Science, and STEM fields. 


*Addition resources can be found in the Primary Sources for Historian page*







Original creative work (i.e. musical score, painting, etc.)

Book or article that analyzes the work

Encyclopedia entry about the creative work


A diary account from an eye-witness of a historical event

Book that interprets the historical event

An index that summarizes and lists reference works

Social Sciences

Notes about an schizophrenic client

Book about schizophrenia

Definition of schizophrenia


Data reporting oceans’ temperature change

Book on climate change

Encyclopedia entry about climate change


Primary sources are materials from the time period of an event created by the people or institutions involved. The materials may be recorded during the event or later on, by a participant reflecting upon the event. Examples include: Letters, diaries, government reports, church records, civil records (birth/death/marriage), literary manuscripts, music scores, recordings, original artworks, choreography notes, scientific lab data, field notes, etc.

Secondary sources are sources that interpret or analyze an historical event or phenomenon.  It is generally at least one step removed from the event is often based on primary sources. Examples include: Scholarly or popular books and articles, and textbooks.
Tertiary sources are sources that identify and locate primary and secondary sources. Examples include: Bibliographies, indexes, abstracts, encyclopedias, and other reference resources. These sources are sometimes available in multiple formats, i.e. some are online, others only in print.
Note: The definition of a source changes dependent on your field of study, application, and interpretation of the source.

It is important to note that these categories are not mutually exclusive. A single item may be primary or secondary (or even tertiary) depending on your research topic and the use you make of the source. For example, a historian may use a newspaper from 2000 as a primary source that documents the 2000 US Presidential Election events first-hand. However, another researcher may use that same newspaper as a secondary source account and rely on primary source recordings of the interviews the reporter conducted before writing the newspaper article. The researcher’s use of the source determines if it is primary, secondary, or tertiary.