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Environmental and Resource Science: Primary & Secondary Sources

This guide is intended for all those studying environmental science and related disciplines.

Source Types in Scientific Literature

Primary and secondary sources can look different depending on the discipline. This guide covers source types in the sciences. If you would like to know more about primary and secondary sources in history and related disciplines, see the history guide.


Your instructor may require you to use specific types of articles for your research, but how can you be sure the article you found meets those requirements? Review the information below, and consider reaching out to your instructor to clarify any assignment details. And don’t forget, the library is here to help! Contact us through the links in the "Need More Help?" box on this page.

Consider the following elements when determining whether a source is an original research article (primary source), or a review article (secondary source):

 

Primary Source:
Research Articles

Secondary Source:
Review Articles

About

Primary research articles present original research, including experiments, observations, or findings conducted directly by the authors.

These types of articles may also be referred to as empirical studies, which can be quantitative or qualitative, or mixed methods (a combination of both).

Review articles summarize, evaluate, and synthesize existing research on a particular topic without presenting new data. They are considered secondary sources.

Articles that synthesize the results of multiple primary studies may be referred to as a literature review, systematic review, or meta-analysis.

Purpose

Shares new data, methods, and insights that advance scientific knowledge.

Provides an overview of current knowledge.

Identifies trends, gaps, and future research directions.

Examples

► All of these examples are from peer-reviewed articles that the library provides access to. Click each title to view the article.

Marine Biology:
Ocean acidification impacts growth and shell mineralization in juvenile abalone (Haliotis tuberculata)

Genetics:
Two novel and correlated CF-causing insertions in the (TG)mTn tract of the CFTR gene

Evolutionary Biology:
Parallel phenotypic evolution in a wolf spider radiation on Galápagos

Marine Biology:
Ecosystem‐based management of coral reefs under climate change

Genetics:
The association between variants in the CFTR gene and nonobstructive male infertility: A meta‐analysis

Evolutionary Biology:
Plant phylogeny as a window on the evolution of hyperdiversity in the tropical rainforest biome

Language

► Keep an eye out for similar language as you examine an article abstract.

"In this study we investigated..."

"The results of this study suggest that..."

"We observed significant differences in..."

"After systematically searching..."

"This article examines recent advances in..."

"Drawing on findings from multiple studies..."

Structure

► Articles will generally follow this structure, with primary research articles focusing on methods, results, and data collected by the authors.

Abstract
A summary of the study's purpose, methods, results, and conclusions.

Introduction
Provides background information, the research question, and the study's objective.

Methods
Details the experimental design, procedures, materials, and analysis methods.

Results
Presents the findings, often with tables, graphs, or other data visualizations.

Discussion
Interprets the results, discusses their significance, and compares them with previous studies.

Conclusion
Summarizes the main findings and their implications.

References
Lists all sources cited in the article.

Abstract
An overview of the topic and the key points covered in the review.

Introduction
Explains the scope, significance, and purpose of the review.

Body
Organized into sections, often by themes or subtopics, to discuss and analyze existing research.

Discussion/Conclusion
Highlights trends, gaps in the research, and future directions for the field.

References
Provides a comprehensive list of studies and sources reviewed.

Finding Articles

The Library Search and most databases make it easy to narrow results to peer-reviewed articles using a peer-reviewed filter. 

However, peer-reviewed or "scholarly" journals contain both primary and secondary articles, so you will still need to evaluate which type it is.

The following videos provide additional guidance for finding and evaluating articles.

► This quick video shows you how to find peer-reviewed articles using Nevada State's Library Search. Keep in mind you will still need to evaluate each article to identify whether it is a primary research article.

► Watch this video for more information about review articles and primary research articles, including how to use signs in the articles to determine the article type:

Article Types in PubMed

The PubMed database has the ability to filter search results by article type. Follow the directions below:

  1. Use the library link above to access PubMed, then enter your search keywords.
  2. On the left sidebar, find the Article Type filter.
  3. Check the box for the article type(s) you are looking for. To see more options, click on "See all article type filters".
    • Primary research article types include:
      • Clinical Trial
      • Observational Study
      • Randomized Controlled Trial
      • Research Article
    • Review article types include:
      • Review
      • Systematic Review
      • Meta-Analysis

Need More Help?

Still have questions? Ask us via quick chat, email library@nevadastate.edu, or meet with a librarian. We're here to help!

Additional Resources

Learn more about research article types: