Primary sources provide first-hand observations or direct evidence concerning a topic under investigation. They are created by witnesses or recorders at or near the time of the event. They have not been filtered through further interpretation or evaluation.
Primary sources may include
Secondary sources are works that analyze, assess or interpret a historical event, era or phenomenon. They may use primary sources to to write a review, critique or interpretation often well after the event.
Secondary sources may include
Tertiary Sources are those used to identify and locate primary and secondary sources.
Tertiary sources may include
Using the Source
What is considered a primary source can vary depending on how you are using the source.
For instance, if you were analyzing how authors of popular magazine articles discussed the Boeing 737 MAX crashes, the magazine articles would serve as your primary sources. However, if you cited from a magazine article for your research paper on airline safety, the magazine would serve as a secondary source.
Different Disciplines
Disciplines may be more or less likely to work with specific types of primary sources. See this chart for examples. If you unsure what is considered a primary source in your discipline, consult with your faculty instructor.
| Discipline | Humanities | Sciences | Social Sciences |
| Primary Source Examples | creative works, diaries, interviews, news footage, maps |
results of experiments, research and clinical trials |
census data, statistics, results of experiments on human behavior |
| Secondary Source Examples | books, journal articles, textbooks |
books, journal articles, textbooks |
books, journal articles, textbooks |
| Tertiary Source Examples | reference materials, databases | reference materials, databases |
reference materials, databases |
This video provides excellent definitions and examples of primary, secondary and tertiary sources.
(1:19) University of Huddersfield Library
Beyond definitions of primary, secondary and tertiary source types, this video provides useful examples of what would be primary, secondary and tertiary sources for research questions in different disciplines. See 1:48.
(2:33) Suffolk County Community College (SCCC) Library
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