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Oak Trees: Primary, Secondary & Tertiary Sources

What is a Primary Source?

A primary source in the sciences is usually a report on the results of an experiment by the person or group who performed it. They are usually published as scientific articles. Primary scientific articles contain high-level vocabulary and will usually present original data, often displayed in tables or charts.

The scientist reports the results of his or her own research. It is not a comment on someone else’s research, although the scientist may refer to someone else’s work in the body of the paper to illustrate the points he/she is trying to prove or disprove. Most scientific journals that are peer-reviewed are likely to contain primary literature. Peer-review means that a panel of experts will review all articles submitted for publication before they are accepted by the journal.

In a primary research article, you will typically see many or all of the following elements clearly presented:

  • An abstract/summary of the research about to be presented
  • Author’s affiliation
  • Introduction with thesis statement
  • review of other literature pertaining to the experiment
  • Methods used to conduct the experiment
  • Materials and equipment used in the experiment
  • Results of the experiment (data) - may include tables, charts, graphs, figures, photographs
  • Discussion of the results
  • Conclusion
  • References/Bibliography

The presence of these components indicate that the author is presenting new data and ideas.

Used by permission of the Waidner-Spahr Library, Dickinson College

What is a Tertiary Source?

A tertiary source is further removed from primary source. It leads the researcher to a secondary source, rather than to the primary source.

Examples of tertiary sources are:

  • Indexes and Bibliographies
  • Encyclopedias and Dictionaries
  • Library catalogs
  • Most textbooks
  • Guidebooks

What is a Secondary Source?

Secondary sources in the sciences are often referred to as REVIEW articles. Review articles summarize, interpret, or analyze the findings of a scientist or group of scientists studying the same thing to summarize the current state of knowledge on a topic. They may discuss the ways in which various researchers' work is related or consider the implications of the research, and pose broad or abstract questions about a field of study. 

Here are two examples of secondary source scientific articles.


The abstract of this article provides clues that it is a review article. 


Tyler, Claudia M. et al. Quarterly Review of Biology. June 2006, vol. 81, no. 2, pp.127-152.

ISSN: 0033-5770

DOI: 10.1086/506025

Abstract: “We review published studies on the demography and recruitment of California oak trees and focus on the widespread dominant species of the foothill woodlands, Quercus douglasii, Q. lobata, and Q. agrifolia, to ascertain the nature and strength of evidence for a decline in populations of these species . . . We summarize the extensive body of research that has been conducted on the biological and physical factors that limit natural seedling recruitment of oaks. The oak "regeneration problem" has largely been inferred from current stand structure rather than by demographic analyses, which in part reflects the short-term nature of most oak research.” [ABSTRACT FROM AUTHOR]


This article provides clues in the title and the scope and methods sections.


Morales, Diego. Trends in Food Science & Technology. Mar. 2021, vol. 109, pp. 116-125.

Document Type: Article

DOI: 10.1016/j.tifs.2021.01.029

Scope and approach: In this review, several biological activities were revised through the scientific literature (antioxidant, immune-modulatory, antiproliferative, hypoglycaemic, hypocholesterolemic, antihypertensive, antimicrobial, etc.) paying attention to bioactive extracts obtained from different oak trees and parts, describing the selected extraction technology, the utilised experimental model, the published results and their potential impact on human health. Moreover, the related strengths and weaknesses were listed to elucidate the current state of the related scientific evidence.

Used by permission of the Waidner-Spahr Library, Dickinson College

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