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Evidence-Based Arguments: Types of Sources to Cite in the Doctoral Capstone

Types of Sources to Cite in the Doctoral Capstone

In the doctoral capstone, students will likely use a variety of sources to support their setting, context, problem, literature review, justification for the method and design, and other information in the document. The bulk of the sources Walden writers use should be from peer-reviewed journal articles, followed by trade journal articles, books, government websites, professional organizations in the field, and other capstones (dissertations/doctoral studies/project studies).

Here is a list of the types of sources commonly used in capstones, with general information regarding each type. We include advice regarding the reliability or strength of the source and therefore the recommended frequency those sources would be cited in the capstone.

Peer-Reviewed (Refereed) Journal Articles

  • This means that the journal had blind reviewers who were experts in the field review the article for relevance, rigor, accuracy, and so on before accepting the article for publication.
  • The bulk of sources students will use in the capstone should be peer-reviewed (or refereed) journal articles. Walden writers should rely mostly on these sources to provide the background, establish the problem, review the literature, as well as justify the method and design.
  • To verify peer review, visit the Walden Library’s Ulrich’s page
  • Examples of commonly cited journals that are peer reviewed:
    • Journal of School Leadership
    • The Qualitative Report
    • The Sociological Quarterly

Non-Peer-Reviewed Journal Articles

  • Some journals are more like trade journals and do not engage in the blind, peer-review process.
  • This means that they are still credible sources but should be used as supplemental support for evidence and arguments that are industry specific.
  • Though there is no guideline for the number of trade journals or other non-peer-reviewed sources, writers should rely less heavily on the arguments and evidence from these sources and use them as supplemental information in areas where there are also peer-reviewed articles cited.
  • Examples of commonly cited journals that are not peer reviewed:
    • Harvard Business Review
    • Nursing in Practice
    • Teaching and Learning


  • Most books are not peer-reviewed-sources and thus have also not gone through the rigorous procedure of verification by experts in the field.
  • Books are still useful sources and often seminal works and could be included in a capstone in a limited number.
  • The process of publication, even for journal articles, is long, but it is even longer for books. The general timeliness of publication often means that books are not the most recent source on a given topic, so areas like the problem statement or social change implications/significance often do not contain book citations.
  • Books are often seminal works, though, and can be relied on for the genesis of a field and background history of a theory. Books are often cited in theory and methods sections, as background and development or rationale.
  • Example of a commonly cited book:
    • Yin, R. K. (2014). Case study research: Design and methods. Sage.

Government Websites

  • Walden writers may find that government websites are appropriate for establishing the background and the problem. National statistics, or even state or local statistics, are often helpful for the justification for the research or specific population information.
  • Because these are not peer-reviewed sources, we suggest that they should be used as supplemental evidence to add support to information from peer-reviewed sources.
  • Examples of commonly cited government websites:
    • U.S. Department of Health and Human Services
    • U.S. Small Business Administration

Other Websites

  • Walden writers may also want to cite professional websites in the capstone.
  • Again, these would not be peer reviewed, so resting an argument on a website alone would not be enough.
  • Use these sources to help establish the context, background, or local problem, again in conjunction with peer-reviewed sources.
  • For information on masking websites that are from the organization under study, check out this additional Form and Style Page on IRB and Confidentiality; scroll to the bottom and view the last Q with examples of how to present this information. In addition, Review the Office of Research and Doctoral Services’s page on Masking Partner Organizations.

News Sources

  • News articles (typically online) may also be used.
  • Walden writers should generally use these sources only to help establish the context or problem—possibly the social change implications and significance—and should generally be avoided in other areas of the capstone.
  • Examples of possible news sources:
    • Minneapolis Star Tribune

Other Capstones (Dissertations, Doctoral Studies, Project Studies)

  • As Walden writers formulate their capstone, it is often helpful to use existing capstones from the field as exemplars or models. We suggest that students review similar capstones from previous Walden students, especially ones that focus on the same topic, method/design, or from their same chair/committee members. Visit the Library page on Walden Dissertations and Theses to search for Walden student capstones.
  • As far as citing other capstones in a capstone, they are not peer-reviewed sources; as student work, they are not held to the same standards as the peer-reviewed work, or even books or websites.
  • Walden writers could use these to discuss the context of current research, not to establish the background of the study, the problem, the theory, or design. Thus, other student work should not be a primary part of or formulation of the main parts of the document.
  • It is acceptable to cite a previous capstone if
    • the work is important to the specific topic or current state of research;
    • the writer of the capstone has not published any documents using the capstone data since graduating (i.e., always check to see if the writer has turned the capstone into a peer-reviewed journal article and cite that instead); or
    • there is no other, recent work, by other authors that is peer reviewed (i.e., it is important to capture the idea/information, but check to see if other authors have done similar or more recent work that is peer reviewed).

Course Resources (Including Course Textbooks and Creswell)

  • Course resources should be avoided in all areas of the capstone.
  • These are intended as learning materials and are not peer reviewed.
  • Instead of citing textbooks by Creswell and other authors, Walden writers should review whom Creswell is citing—often seminal methodologists or experts in the field—and retrieve those sources instead.