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Primary, Secondary and Tertiary Sources

Definitions and examples of primary, secondary and tertiary sources

Defining Primary, Secondary and Tertiary Sources

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

  • Original Documents: diaries, speeches, letters, interview transcripts, news footage, autobiographies, reports, census records, data from an experiment
  • Creative Works: poetry, plays, novels, music scores, films, paintings
  • Objects: clothing, buildings, tools, furniture

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

  • journal articles, editorial articles, literacy criticism, book reviews, biographies, textbooks

Tertiary Sources are those used to identify and locate primary and secondary sources.

Tertiary sources may include

  • Reference Works: encyclopedias, abstracts
  • Lists or Collections: bibliographies, finding aids
  • Search Tools: library database or catalog, indexes

Primary, Secondary and Tertiary Sources in Disciplines

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

Video: The Information Landscape

This video provides excellent definitions and examples of primary, secondary and tertiary sources.

(1:19) University of Huddersfield Library

(1:19) University of Huddersfield Library

Types of Sources - Primary, Secondary, and Tertiary (Video Tutorial)

Check out this short video (2:23) from Suffolk County Community College Library to understand how primary, secondary, and tertiary sources vary by discipline. Beyond definitions of source types, this video provides useful examples of what would be primary, secondary and tertiary sources for research questions in different disciplines.