Knowing the difference between primary and secondary sources will help you determine what types of sources you may need to include in your research essay. In general, primary sources are original works (original historical documents, art works, interviews, etc.), while secondary sources contain others’ insights and writings about those primary works (scholar articles about historical documents, art works, interviews, etc.).
While many scholarly sources are secondary sources, you will sometimes be asked to find primary sources in your research. For this reason, you should understand the differences between primary, secondary, and tertiary sources.
- Primary sources allow researchers to get as close as possible to original ideas, events, and empirical research as possible. Such sources may include creative works, first hand or contemporary accounts of events, and the publication of the results of empirical observations or research. These include diaries, interviews, speeches, photographs, etc.
- Secondary sources analyze, review, or summarize information in primary resources or other secondary resources. Even sources presenting facts or descriptions about events are secondary unless they are based on direct participation or observation. These include biographies, journal articles, books, and dissertations.
- Tertiary sources provide overviews of topics by synthesizing information gathered from other resources. Tertiary resources often provide data in a convenient form or provide information with context by which to interpret it. These are often grouped together with secondary sources. They include encyclopedias and dictionaries.
| Subject | Primary | Secondary | Tertiary |
| Art | Painting | Critical review of the painting | Encyclopedia article on the artist |
| History | Civil War diary | Book on a Civil War battle | List of battle sites |
| Literature | Novel or poem | Essay about themes in the work | Biography of the author |
| Political science | Geneva Convention | Article about prisoners of war | Chronology of treaties |
| Agriculture | Conference paper on tobacco genetics | Review article on the current state of tobacco research | Encyclopedia article on tobacco |
| Chemistry | Chemical patent | Book on chemical reactions | Table of related reactions |
| Physics | Einstein’s diary | Biography on Einstein | Dictionary of relativity |
Analyze your topic/working thesis to determine the types of sources that can help with support. For example, if your topic deals with Van Gogh’s use of pale green and what it connotes in his later paintings, you will need to couple evidence from primary sources (images of the paintings themselves) with secondary sources (other scholars’ views, discussions, and logical arguments about the same topic). If your working thesis deals with the benefits of regular exercise for older adults in their 70s-90s, you may couple evidence from primary sources (uninterpreted data from research studies, interviews with older adults or experts in the field) with secondary sources (interpretations of research studies). In some cases, you may find that your research is mostly from secondary sources and that’s fine, depending on your topic and working thesis. Just make sure to consider, consciously, the types of sources that can best be used to support your own ideas.
The following video provides a clear overview of primary and secondary sources.