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Primary, Secondary & Tertiary Sources: About

Guide on Identifying Primary, Secondary and Tertiary Sources

Identifying Primary, Secondary and Tertiary Sources

What are Primary Sources? 

A primary source is a first hand testimony, document, speech or other evidence that gives insight into a particular person or an event. They are often created during the time period which is being studied but can also be produced later by eyewitnesses or participants.

Book covers, magazines, newspapers, and notebooksPrimary 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. 

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. Moreover, secondary sources often rely on other secondary sources and standard disciplinary methods to reach results, and they provide the principle sources of analysis about primary sources.

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.

The distinctions between primary, secondary, and tertiary sources can be ambiguous. An individual document may be a primary source in one context and a secondary source in another. Encyclopedias are typically considered tertiary sources, but a study of how encyclopedias have changed on the Internet would use them as primary sources. Time is a defining element.

While these definitions are clear, the lines begin to blur in the different discipline areas. See box below for examples. 

(Adapted from: VirginaTech Library under CCBY 4.0)

Primary, Secondary & Tertiary Sources (video)

Learn the differences among primary, secondary, and tertiary sources while seeing examples for each type of resource. 

(Created by Suffolk County Community College Library.)

Examples in different discipline areas

In the humanities and social sciences, primary sources are the direct evidence or first-hand accounts of events without secondary analysis or interpretation. A primary source is a work that was created or written contemporary with the period or subject being studied. Secondary sources analyze or interpret historical events or creative works.


Primary sources

Secondary sources

Tertiary sources

  • Diaries
  • Interviews
  • Letters
  • Original works of art
  • Photographs
  • Speeches
  • Works of literature
  • Biographies
  • Dissertations
  • Indexes, abstracts, bibliographies (used to locate a secondary source)
  • Journal articles
  • Monographs
  • Dictionaries
  • Encyclopedias
  • Handbooks
primary source is an original document containing firsthand information about a topic. Different fields of study may use different types of primary sources. secondary source contains commentary on or discussion about a primary source. The most important feature of secondary sources is that they offer an interpretation of information gathered from primary sources. tertiary source presents summaries or condensed versions of materials, usually with references back to the primary and/or secondary sources. They can be a good place to look up facts or get a general overview of a subject, but they rarely contain original material.


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

(Adapted from: VirginaTech Library under CCBY 4.0 )

In the sciences, primary sources are documents that provide full description of the original research. For example, a primary source would be a journal article where scientists describe their research on the genetics of tobacco plants. A secondary source would be an article commenting or analyzing the scientists' research on tobacco.

Primary sources

Secondary sources

Tertiary sources

  • Conference proceedings
  • Interviews
  • Journals
  • Lab notebooks
  • Patents
  • Preprints
  • Technical reports
  • Theses and dissertations
  • Monographs
  • Reviews
  • Textbooks
  • Treatises
  • Compilations
  • Dictionaries
  • Encyclopedias
  • Handbooks
  • Tables
These are where the results of original research are usually first published in the sciences. This makes them the best source of information on cutting edge topics. However the new ideas presented may not be fully refined or validated yet. These tend to summarize the existing state of knowledge in a field at the time of publication. Secondary sources are good to find comparisons of different ideas and theories and to see how they may have changed over time. These types of sources present condensed material, generally with references back to the primary and/or secondary literature. They can be a good place to look up data or to get an overview of a subject, but they rarely contain original material.


Subjects Primary Secondary Tertiary
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

(Source: VirginaTech Library under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.)

Cycle of Information

Your professor has instructed you to get primary or secondary materials for your research project, and you are confused. If you understand the publication cycle of information, you will then understand what your professor means when they request primary or secondary materials. Chart One of this guide defines the different stages of the cycle of information.
  • Timing of the event recorded--If the article was composed close to the time of the event recorded, chances are it is primary material. For instance, a letter written by a soldier during the Vietnam War is primary material, as is an article written in the newspaper at the time of the Vietnam War. However, an article written about the Vietnam War in recent years would be secondary material.
  • Rhetorical aim of the written item--Often, an item that is written with a persuasive, or analytical, aim is secondary material. These materials have digested and interpreted the event with a certain detachment not characteristic of primary materials.
  • Context of the researching scholar--Primary materials for a critic studying the literature of the Vietnam War are different from primary materials for a research scientist studying the affects of Agent Orange syndrome. The critic's primary materials are the poems, stories, and films of the era. The research scientist's primary materials would be the medical records of those person exposed to Agent Orange.


DEFINITIONS Sources that contain raw, original, non interpreted and unevaluated information. Sources that digest, analyze, evaluate and interpret the information contained within primary sources. They tend to be argumentative. Sources that compile, analyze, and digest secondary sources. They tend to be factual.
TIMING OF PUBLICATION CYCLE Primary sources tend to come first in the publication cycle. Secondary sources tend to come second in the publication cycle. Tertiary sources tend to come last in the publication cycle.
FORMATS--depends on the kind of analysis being conducted. Often newspapers, weekly and monthly-produced magazines; letters, diaries. Often scholarly periodicals and books. (Professors like these.) Often reference books.


(studying the Vietnam War)

Newspaper articles, weekly news magazines, monthly magazines, diaries, correspondence, diplomatic records. Articles in scholarly journals analyzing the war, possibly footnoting primary documents; books analyzing the war. Historical dictionaries, encyclopedias and almanacs. Examples: Historical Dictionary of Vietnam; The Vietnam War, An Almanac

Example:Literary Critic

(studying the literature of the Vietnam War)

Novels, poems, plays, diaries, correspondence. Articles in scholarly journals analyzing the literature; books analyzing the literature; formal biographies of writers of the war. Literary dictionaries, bibliographies. Examples: A Bibliography of the Literature of the Vietnam Conflict; Dictionary of Literary Biography. 


(studying the effects of the Vietnam syndrome)

Article in a magazine that reports research and its methodology; notes taken by a clinical psychologist. Articles in scholarly publications synthesizing results of original research; books analyzing results of original research. Guidebooks, Encyclopedia, Handbooks. Examples: Diagnostic and Statistical Manual of Mental Disorders; The Encyclopedic Dictionary of Psychology. 


(studying Agent Orange exposure)

Article in a magazine reporting research and methodology. Articles in scholarly publications synthesizing results of original research; books doing same. Tables, Dictionaries, Encyclopedias, Handbooks. Example: Agent Orange and Vietnam: An Annotated Bibliography.

(Source: Guide by UNCW William Madison Randall Library)

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