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Physician Assistant

Types of sources

level of origin graphic defining primary, secondary and tertiary sources

Graphic developed by Angie Paul, WSU University Libraries.  Here is a similar graphic to the one above developed by the University of California, San Diego.


Sources can be defined at least two different ways. When people use the phrase "types of sources" they may be referring to the:

  1. Format and delivery method of the information source (book, article, movie, blog entry, etc.)
  2. Level or distance from the original source of information (tertiary, secondary, or primary)


For an overview of your topic, use tertiary sources:

Tertiary sources provide overviews of topics by compiling, indexing, or organizing primary and secondary sources. These types of sources should be used only for background information and are not usually included in the bibliography of a college-level research paper.  They include handbooks, textbooks, subject-specific reference sources, general encyclopedias, and bibliographies.

For in-depth information about your topic, use secondary sources:

Secondary sources are materials that provide analyses or interpretations of primary sources. Typically, the creator of a secondary source does not have first-hand experience with the topic's events or conditions.  These sources can include non-fiction books and other monographs, some textbooks, scholarly journal articles, literary criticisms, statistical summaries, trade publications, newspapers, popular magazines, and documentary movies.  For further information, click on the tab above.

For first-hand information about your topic, use primary sources:

Primary sources are first-hand accounts that are directly related to a topic. These sources can include diary entries, raw data, interviews (including interviews in documentary movies), music and other sound recordings, blogs, photographs, some scholarly journal articles, newspaper articles, books, or other types of manuscripts.  For further information, click on the tab above.

Image of an 8-track player

Steve. (2005, Feb. 18). 8-Track. Retrieved from Used under the Creative Commons License.

A source may be available in print, or it may be electronic. Titles available in a physical format, such as books, are often also electronically available.  Other forms of media, such as YouTube videos, inherently have an electronic format.  If a work is available in both a print and digital version, you, the researcher, must decide which method of delivery you prefer or which is most readily available at time of need.

Format can also affect whether a work may be considered a primary source or not.  Most books and articles are available either in print or online. Books may be available in paperback, hardback, large print or other types of editions or formats. The format and edition of an information source may affect whether the item is considered to be a primary source (the original source of information or an exact replica) or not.

Front covers of different issues of print journals

The Wiley Asia Blog. (2012, Sept. 18). Nutrition Journals. Retrieved from Used under the Creative Commons License.

Most books, articles, and other information sources are considered to be secondary sources. This determination, however, depends on the purpose of your research. If you are writing a research paper about the Civil Rights movement, Maya Angelou's I Know Why the Caged Bird Sings would be a secondary source because that is not a central theme in this book, although it is peripherally related.  If, by contrast, you are writing about racism and sexism in America, this book would be considered a primary source because it is a first-hand account of her experiences with these issues.

Types of secondary sources typically include, but are not limited to, non-fiction books and other monographs, some textbooks, some scholarly journal articles, literary criticisms, statistical summaries, trade publications, newspapers, popular magazines, and documentaries.

While it is not an exact fit, the secondary literature is where you will find most scholarly sources.  Generally, a scholarly source is written by an expert in the given field and goes through the peer-reviewed process (see the "What makes an article peer-reviewed vs. scholarly vs. non-scholarly" box on this page).

While articles from academic journals are perhaps the most prominent of scholarly sources, these sources exist in many forms. They may also be books, conference proceedings, or other sources that match scholarly criteria.  The other sub-tabs under the Evaluating information section of this guide (which is indeed the section you are currently viewing) offer further guidance on understanding and identifying secondary resources, and comparing them against scholarly criteria to evaluate if they will be of value to your research.

Primary source books (2010, Mar. 31). -- Opening Up Primary Legal Materials. Retrieved from Used under the Creative Commons License.

A primary source is an original source of information on a topic, usually created at the time of study.  As such, primary sources are usually at least somewhat biased, as they are not subject to the same level of removal from a topic that accompanies secondary or tertiary sources.


Primary resources are discipline-specific.  What defines a primary resource varies slightly with each discipline.  Examples include:

  • Archaeology/Anthropology: An artifact or object that provides evidence of a society, such as clothing, farming tools, household items, and buildings
  • Arts and Literature: The original artistic or literary work that forms the basis for a criticism or review, such as feature films, musical compositions, sound recordings, paintings, novels, plays, and poems
  • Biology: Research or lab notes, genetic evidence, plant specimens, technical reports, and other reports of original research or discoveries (e.g., conference papers and proceedings, dissertations, scholarly articles)
  • Engineering: Design notes, patents, conference proceedings, technical reports, and field surveys
  • History: Government documents (e.g., treaty, birth certificate), photographs, store account books, artifacts (such as those listed for archaelogy/anthropology), maps, legal and financial documents, and census records


Examples of primary sources:

  • News Sources: Newspapers, news blogs, news magazines and similar sources are usually written by professional journalists. News sources are typically not as technical as scholarly articles, and are a good choice when the researcher wants information about events as the event was currently perceived at publication. Newspapers may be found from the 1700's to current issues in the WSU University Libraries.  As with other publications, news sources are used as primary sources of information when the researcher is looking for contemporary opinions and/or personal experiences. 

  • Books: Similar to news sources, a book would be a primary source if (among other criteria) it is the original source material for one or more thoughts or opinions, documents original research, or is autobiographical.

  • Handbooks and Standards: these sources often contain information required for maintaining technical norms and integrity. Engineering, grammar, and many other fields use handbooks and standards to establish required benchmarks. Handbooks and standards are considered to be primary sources when used for this type of information.

  • Legal Materials: legal materials, including statutes, bills, congressional reports, hearings, court records, case notes, brochures and other documents produced by federal, state and local governments are original sources of information. Some documents, such as court proceedings, also include transcripts of conversations. 

  • Patents: there are many types of patents.  Like standards, patents provide information about the specifications of a design, a process, or other product or idea. Although most patents contain images, a textual description accompanies each patent. 

  • Manuscripts: Handwritten or typed notes, journals and diaries, financial ledgers, and other handwritten records can record personal, historical experiences. Although this medium may be digitized as PDF or other image files, the original must be on paper to be defined as a manuscript.

  • Artifacts: human-made objects, typically of cultural or historical interest, are called artifacts. Artifacts are most often used as primary sources for cultural anthropology or historical research, but tools, technology and other objects may be useful information sources in other fields as well. 

  • Maps: maps are diagrammatic representations of areas of land, sea or sky which usually illustrate spatial arrangement or distribution of something, such as population. These primary sources may still include bias, as with statistics and other sources -- think about what information may have been excluded. The WSU Special Collections offers a rich collection of maps, both in print and online.

  • Photographs: photographs document historical and contemporary events or relationships, such as the history of an organization or location, and provide evidence of an historical event. WSU Special Collections includes photographs and other images.

  • Speeches and Interviews: speeches and interviews may be found in audio formats or transcribed.

  • Musical Recordings: criticisms and reviews of music, musicals, and other performances require reference to the original item being reviewed -- in other words, the primary source material. WSU University Libraries has several streaming media databases, which offer access to different musical recordings online (WSU login required).

  • Motion Pictures: Similar to musical recordings, criticisms and reviews of films, television shows, and other motion pictures require reference to the original item being reviewed. Documentaries may also be primary sources if interviews, original footage and other first-hand experiences are included. WSU University Libraries has several streaming media databases, which offer access to different musical recordings online (WSU login required).

  • Blogs and Social Media: these sources are electronic versions of personal opinions and experiences. Writings by specialists, professional journalists, and others considered to be authorities in their field can be credible sources, depending on their specialty and the topic of the writing. If the researcher needs to review opinions and see online dialog among members of a scholarly discipline, blogs and social media can be primary sources. 

  • Research Data and Statistics: numerical information may be represented as raw data sets, or in a statistical summary. WSU University Libraries has access to the SAGE StatsSAGE Research Methods, and SAGE Research Methods Cases databases, which offer literature and explanations of how to interpret data and statistics (WSU login required).

What makes information peer-reviewed vs. scholarly vs. non-scholarly? Which type of source should I use?

Image of man thinking

There is a nuanced distinction between peer-review and scholarship, which typically doesn't matter when evaluating sources for possible citation in your own work.  Peer-review is a process through which editors of a journal have other experts in the field evaluate articles submitted to the journal for possible publication.  Different journals have different ways of defining an expert in the field.  Scholarly works, by contrast have an editorial process, but this process does not involve expert peer-reviewers.  Rather, one or more editors, who are themselves often highly decorated scholars in a field, evaluate submissions for possible publication.  This editorial process can be more economically driven than a peer-review process, with a greater emphasis on marketing and selling the published material, but as a general rule this distinction is trivial with regard to evaluating information for possible citation in your own work.

What is perhaps a more salient way of thinking about the peer-review / scholarship distinction is to recognize that while peer-reviewed information is typically highly authoritative, and is generally considered "good" information, the absence of a peer-review process doesn't automatically make information "bad."  More specifically, the only thing the absence of a peer-review process means is that information published in this manner is not peer-reviewed.  Nothing more.  Information that falls into this category is sometimes referred to as "non-scholarly" information -- but again, that doesn't mean this information is somehow necessarily problematic.

Where does that leave you in terms of deciding what type of information to use in producing your own work?  That is a highly individual decision that you must make.  The Which type of source should I use? tab in this box offers further guidance on answering this question, though it is important to be aware that many WSU instructors will only consider peer-reviewed sources to be acceptable in the coursework you turn in.  You can ask your instructor for his or her thoughts on the types of sources s/he will accept in student work.

Image: Martin Grater. (2017, Nov. 1). Deep Thought. Retrieved from Used under the Creative Commons License.

Image of man thinking

Your topic and research question or thesis statement will guide you on which resources are best.  Sources can be defined as primary, secondary and tertiary levels away from an event or original idea. Researchers may want to start with tertiary or secondary source for background information. Learning more about a topic will help most researchers make better use of primary sources.

While articles from scholarly journals are often the most prominent of the sources you will consider incorporating into your coursework, they are not the only sources available to you.  Which sources are most appropriate to your research is a direct consequence of they type of research question you decide to address.  In other words, while most university-level papers will require you to reference scholarly sources, not all will.  A student in an English course writing a paper analyzing Bob Dylan's lyrics, for example, may find an interview with Dylan published in Rolling Stone magazine a useful source to cite alongside other scholarly works of literary criticism.

The WSU University Libraries' What Sources Should I Use? handout, as well as the other sub-tabs under the Evaluating information section of this guide (which is indeed the section you are currently viewing) offer further guidance on understanding and identifying scholarly resources, and comparing them against different criteria to evaluate if they will be of value to your research.  How many non-scholarly works (if any) you are at liberty to cite alongside scholarly ones is often a question to ask of your professor.  Some may not want you to cite any, whereas others may be ok with some non-scholarly works cited alongside scholarly ones.

Image: Brett Woods. (2006, Jan. 6). Deep Thoughts. Retrieved from Used under the Creative Commons License.

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