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Natural Resources and the Environment Subject Guide — Starting Your Research Project

Description of databases, reference material, journals, books, etc. available for natural resources research.

Beginning Research Help

For help getting started with your research project, consult the general Research Quick Start guide below. 


Science writing assignments also often call for peer reviewed articles that are either primary or review articles.What do those terms mean? This page should help you understand what these concepts are so you can conduct your research successfully.

Peer Review Basics

Peer review (also known as "Refereed") happens in all parts of academia. It is especially important in the sciences because peer reviewed journal articles are the primary source of new information and discoveries in the sciences. Peer review has developed over many years as the primary system to make sure accurate, reliable and original research findings are published in the journal literature. The video "Peer Review in 3 Minutes" offers a quick explanation of the peer review process.

Is This Article Peer Reviewed?

First make sure it IS a research article. Not every article in a journal is about research, they can include editorials, book reviews and other types of articles. 

To verify the peer reviewed aspect of a journal several options are available to you:

  • Look for the dates of peer review on the first page of the PDF version of the article. Usually it will have three dates: Reviewed, Accepted, and Published. Those are the stamp of peer review and verify the peer review process. But even if there are only two such dates, say Reviewed and Accepted, that is enough to established that the article has been through peer review. However not every publisher puts these datas on the article's first page. 
  • Go to the journal's home page and check the "About" section. Most peer reviewed journals will include information about their process here.
  • Go to the database Ulrich's Periodicals Directory at your library's website. Search for the journal name and in the Basic Description section look for the Refereed category - it should say "Yes" for a peer reviewed journal.

How to Read a Scientific Article

Research articles are written for researchers and so can be difficult to understand for undergraduate students. Here are some sources to help you learn how to read research articles.

Primary, Secondary, & Tertiary Sources

Informational sources can be classified roughly into three groups - primary, secondary, and tertiary - that reflect their originality. These groups are defined generally below.


Primary sources are original, uninterpreted information.
Unedited, firsthand access to words, images, or objects created by persons directly involved in an activity or event or speaking directly for a group. This is information before it has been analyzed, interpreted, commented upon, spun, or repackaged. Depending upon the context, these may include research reports, sales receipts, speeches, e-mails, original artwork, manuscripts, photos, diaries, personal letters, spoken stories/tales/interviews, diplomatic records, etc.

Think of physical evidence or eyewitness testimony in a court trial.


Secondary sources interpret, analyze, or summarize.
Commentary upon, or analysis of, events, ideas, or primary sources. Because they are often written significantly after events by parties not directly involved but who have special expertise, they may provide historical context or critical perspectives. Examples are scholarly books, journals, magazines, criticism, interpretations, and so forth.

Think of a lawyer's final summation or jury discussion in a court trial.


Tertiary sources compile, index, or organize sources. 
Sources which analyzed, compiled and digest secondary sources included mostly in abstracts, bibliographies, handbooks, encyclopedias, indexes, chronologies, etc.

Think of an index that lists all the cases heard by this court during the year.

In the humanities and social sciences, primary sources are the direct evidence or first-hand accounts of events without secondary analysis or interpretation. A primary source is a work that was created or written contemporary with the period or subject being studied. Secondary sources analyze or interpret historical events or creative works.

Primary sources

  • Autobiographies
  • Diaries
  • Interviews
  • Letters
  • Original works of art
  • Photographs
  • Speeches
  • Works of literature

A primary source is an original document containing firsthand information about a topic. Different fields of study may use different types of primary sources.

Secondary sources

  • Biographies
  • Dissertations
  • Indexes, abstracts, bibliographies (used to locate a secondary source)
  • Journal articles
  • Book about a primary source

A secondary source contains commentary on or discussion about a primary source. The most important feature of secondary sources is that they offer an interpretation of information gathered from primary sources.

Tertiary sources

  • Dictionaries
  • Encyclopedias
  • Handbooks

A tertiary source presents summaries or condensed versions of materials, usually with references back to the primary and/or secondary sources. They can be a good place to look up facts or get a general overview of a subject, but they rarely contain original material.


Subject Primary Secondary Tertiary
Art Painting Critical review of the painting Encyclopedia article on the artist
History Civil War diary Book on a Civil War Battle List of battle sites
Literature Novel or poem Essay about themes in the work Biography of the author
Political science Geneva Convention Article about prisoners of war Chronology of treaties

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In the sciences, primary sources are documents written by the person(s) who conducted the original research. For example, a primary source would be a research article where scientists describe their methodology, results, and conclusions about the genetics of tobacco plants. A secondary source would be an article commenting or analyzing the scientists' research on tobacco.

Primary sources

  • Conference proceedings
  • Original research articles
  • Lab notebooks
  • Data sets
  • Patents
  • Technical reports

These sources are where the results of original research are usually first published in the sciences. This makes them the best source of information on cutting edge topics. However the new ideas presented may not be fully refined or validated yet.

Secondary sources

  • Books
  • Review Articles

These sources tend to summarize the existing state of knowledge in a field at the time of publication. Secondary sources are useful places to learn about your topic in depth. They are useful places to find comparisons of different ideas and theories and to see how they may have changed over time.

Tertiary sources

  • Compilations
  • Dictionaries
  • Encyclopedias
  • Textbooks
  • Handbooks

These types of sources present condensed material, generally with references back to the primary and/or secondary literature. They can be a good place to look up data or to get an overview of a subject, but they rarely contain original material.


Subjects Primary Secondary Tertiary
Agriculture Primary Research article paper on dairy microbiology Review article on the current state of dairy microbiology Encyclopedia article on dairy microbiology
Chemistry Chemical patent Book about organic chemical reactions Handbook of related organic reactions
Physics Conference proceeding on high energy physics A book about the current state of the field of high energy physics Dictionary of high energy physics

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Recognizing a Primary Research Article

In the sciences, primary research articles have a similar basic structure. Most will have these sections or a subset of them, but all should have a "methods" section and a "results" section. 

chart of article structure