Finding Sources

Primary Source

What is a primary source?

In science, when we talk about primary sources we mean research articles written by the person(s) who did the research. Generally, primary sources are considered reliable only if they are peer-reviewed.

What is a secondary source?

Textbooks and review articles are secondary sources because they do not present new information; instead, they are written using multiple primary sources. Textbooks are easy to identify but review articles can be harder to identify because they are often published alongside primary source articles. Some journals kindly indicate that an article is a review article at the start. Others are not so obvious but can usually be identified because they do not present any new data (if data are presented they are always accompanied by a reference) and they do not have a methods section.

What is meant by peer-reviewed?

Before a paper is published in a peer-reviewed journal, it is critically read by other scientists who are familiar with the type of research that is being published. Generally papers are reviewed by two or three independent scientists. The reviewers read the paper critically, and give the journal editor their opinion on the validity of the study (e.g. did the researchers use appropriate methods and controls to produce the results being presented?) and the importance of the study (will the results and analysis presented in the paper add to the overall understanding in the field?). Reviewers will commonly make suggestions to improve the submitted paper.

How do I recognize a primary source?

Generally primary sources are published as articles in a scientific journals. Scientific journals are a bit like any popular magazine you might read with a few notable exceptions: The main purpose of a scientific journal is to present science, not to make money via advertising; therefore, each article in the journal will be presented continuously (any advertising is placed so as not to disrupt the flow of the science article).

The following are generally true of primary literature papers

  • They are short. Depending on the journal, the articles are generally between 2 and 15 pages in length.
  • They include a methods section or some description of the methods used.
  • They include new results (you can tell the results have not been previously published because they are not cited). Depending on the journal, new results are presented in a results section, or in a combined results/discussion section.
  • Usually at least one table or figure will be present.

Reading and Understanding Sources

Reading primary literature can be very daunting for undergraduate students.
For some excellent tips please see "How to read and understand a scientific paper: a guide for non-scientist".

Finding Sources

Screencast: Finding papers online using URegina resources (password is "biology")

Google Scholar

Google Scholar is great for finding general, but reputable, scientific papers.

Tutorial Searching Using Google Scholar

Electronic Databases

Electronic databases are better to use when you have a more specific idea about what you are looking for because each database covers a specific academic discipline. For example AGRICOLA covers everything agriculture related. Most databases will include both primary and secondary publications.

The U of R Library has subscriptions to a huge list of databases. You can use these while on a campus network, or from home using EZProxy (note that you can't just access these from anywhere because the subscriptions cost money).

Go to the Dr. John Archer Library homepage and, after clicking on the "Databases" tab, search for "Biology" in the "Find Database by Subject" field. Alternatively, type in the name of the specific database you wish to use, e.g. PubMed, Web of Science, or other.

Web of Science / Web of Knowledge

The Web of Science is one of the most comprehensive science-literature databases available. It covers all of the major journals in all branches of science as far back as 1898.

Web of Science tutorial.


PubMed describes itself as citation database of biomedical literature. It includes citations from primary and secondary sources (a.k.a. books). It covers not only biomedical topics, but also literature in the fields of life sciences, behavioral sciences, chemical sciences, and bioengineering. It is particularly useful if you are looking for information in the molecular biology or biochemistry. It will not be as useful for plant or environmental information.
To learn how to use PubMed, please see the PubMed Help at NCBI.