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Types of Sources

Types of Sources

Author: Sophia Tutorial

Differentiate between primary, secondary, and tertiary sources.

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what's covered
In this lesson, you will learn about the three kinds of sources writers use to support their claims and thesis statements, as well as how to identify and use them. Specifically, this lesson will cover:
  1. Sources as Evidence
    1. Primary Sources
    2. Secondary Sources
    3. Tertiary Sources
  2. Source Examples
    1. Art
    2. Physics
    3. Sociology
    4. Drama

1. Sources as Evidence

In academic writing, you will often need to use sources, identified through research, to support the claims in your essays. The use of sources involves a process that includes analysis, coding, paraphrasing, and summarizing. The purpose of this process is to demonstrate that the ideas and claims in an essay are more than the writer's opinions. By supporting arguments with fact-based evidence, effective research increases the audience's willingness to accept them.

Research is also one of the ways in which writers participate in an academic conversation involving the ideas, topics, and issues related to an essay. During research, writers often locate more sources than they can use. It is important to choose the sources that best suit your purposes.

When conducting research, you want to:

  • Select sources that are most closely aligned to your thesis.
  • Select sources that are most likely to appeal to your readers.
  • Select sources that are necessary to establish the credibility of your ideas.
There are three types of sources you are likely to encounter in your research. We will now examine each of them in more depth.

1a. Primary Sources

Primary sources are documents or objects that are as close to the source topic or event as possible. These sources are identified through careful analysis by writers. For most essays, primary sources are required to build original, relevant ideas and claims.

Primary sources come in many forms, but the following are some of the most common:

  • Literary works, including novels, poems, short stories and creative nonfiction, as well as films, TV shows, songs or albums, paintings, and other works of art and creative media
  • Historical artifacts, including photographs, news articles, legal records, census records, physical objects, and firsthand accounts (written or oral)
  • Letters, diaries, interviews, and speeches
  • Scientific material, including lab reports, published research articles and conference proceedings, patents, mathematical proofs, and technical documents
All of these can be used as primary sources: They can be analyzed and discussed to advance the goals of an essay.

term to know
Primary Source
A document or object that is as close to the source topic or event as possible.

1b. Secondary Sources

Secondary sources are one of the most common types of sources used to support research papers. They are expressions of original research related to primary sources; therefore, they are one step further removed from the source topic or event.

However, secondary sources can sometimes be more useful than the primary sources to which they are related. They often contain analysis of, and thoughts about, the primary source that can help writers to understand it better.

Secondary sources usually follow specific conventions related to a particular field of study. Writers in many fields can use secondary sources for several reasons:

  • To discover what experts think about the primary source or topic
  • To demonstrate a writer's involvement in the academic conversation about the primary source or topic by referring to the metaphorical conversation about it
  • To provide more support for the writer's ideas and claims
  • To demonstrate areas of difference (including disagreement) between the writer's ideas and those of other writers
The most common forms of secondary sources include articles (from academic journals and other publications), books, opinion-based essays (e.g., editorials), biographies, textbooks, and treatises.

term to know
Secondary Source
An expression of original research related to a primary source.

1c. Tertiary Sources

Tertiary sources are compilations or syntheses of research, data, or other information. In addition to providing factual information, they sometimes present an overview of a field or topic. Because tertiary sources are not primary or based on original research, they are usually less valuable and relevant than primary and secondary sources.

Still, tertiary sources are sometimes a good place to begin researching a topic because they often lead to the secondary and primary sources from which they were compiled or synthesized.

Tertiary sources include dictionaries and encyclopedias (both physical and online). Handbooks, tables, and literary reviews that summarize a collection of related secondary sources may also be useful tertiary sources.

Student writers should remember that some classes, professors, and assignments do not allow citation of tertiary sources (e.g., Wikipedia) as research sources.

Tertiary sources can be useful during preliminary or introductory research (i.e., research that increases writers' understanding of a topic, and directs them to secondary and primary sources).

term to know
Tertiary Source
A compilation or synthesis of research, data, or other information.

2. Source Examples

The following examples of the three types of sources in different fields of study illustrate how these source types relate to each other.

2a. Art

The first example examines the subject of art. As the table below indicates, a primary source in this field might be the painter Gustav Klimt's "Tree of Life." This painting is an art object that a writer can analyze. There are also secondary sources that could be used (e.g., a book on Gustav Klimt's career as an artist that includes an analysis of the source material).

As a tertiary source, an encyclopedia entry on Austrian painters (including Klimt) could be consulted. This source would probably include basic information about the primary source (i.e., "Tree of Life"— one of Klimt's most famous paintings). However, the encyclopedia entry alone is not sufficient for a writer or researcher.

Subject Primary Secondary Tertiary
Art Gustav Klimt's "Tree of Life" Book on Klimt's career Encyclopedia on Austrian painters

2b. Physics

Next, consider a different kind of source within the subject of physics: a mathematical theorem about fluid dynamics. This theorem could be analyzed, argued, and written about directly. Secondary sources, such as a scholarly, peer-reviewed article about the theory's relevance to modern engineering, could also be identified and evaluated.

Tertiary sources that provide material on the primary subject could, in this example, include an introductory physics textbook that contains basic information. This source is only appropriate to introduce a researcher to the topic; it is not sufficient for citation.

Subject Primary Secondary Tertiary
Physics Theorem of fluid dynamics Scholarly article explaining its relevance Introductory Physics textbook

2c. Sociology

The following example involves sociology. Many primary sources are available in this field; in this example, the primary source is The Autobiography of Malcolm X. Secondary sources about this book could include a historical book about Malcolm X written by another author (e.g., one that compares the education he gave himself in prison to his schooling as a child).

A tertiary source in this case could be a Wikipedia page about the civil rights movement that mentioned Malcolm X.

Subject Primary Secondary Tertiary
Sociology Malcolm X's autobiography Book about Malcolm X and his jailhouse education Wikipedia page about the civil rights movement

2d. Drama

Here's an example in the field of drama. A primary source in this area could be a theater's 1998 performances of an adaptation of Samuel Beckett's "Waiting for Godot," while a drama critic's published review of the adaptation would be a great secondary source.

A pamphlet distributed by the theater that chronicles all of the performances of this play during the '90s (and which might refer to the critic's review) might also be a useful source— if the critic was well-respected and the review was positive.

Subject Primary Secondary Tertiary
Drama 1998 Adaptation of "Waiting for Godot" Drama critic's review Pamphlet about the theater's history

As you can see, primary, secondary, and tertiary sources can all be useful in the research process. Their importance depends on the writer's needs and purpose.

In this lesson, you learned that writers use sources as evidence to support their claims and thesis statements. There are three types of sources: primary sources, secondary sources, and tertiary sources. An examination of source examples in the fields of art, physics, sociology, and drama demonstrated how all three source types can be useful across a variety of subjects.

Best of luck in your learning!

Terms to Know
Primary Source

A document or object that is as close to the source topic or event as possible.

Secondary Source

An expression of original research related to a primary source.

Tertiary Source

A compilation or synthesis of research, data, or other information.