Different sources, different evaluations

The process of peer review can be defined as:
“… the process of subjecting an author’s [..] work, research, or ideas to the scrutiny of others who are experts in the same field, before a paper describing this work is published in a journal. The work may be accepted, considered acceptable with revisions, or rejected…. This process encourages authors to meet the accepted standards of their discipline and prevents the dissemination of irrelevant findings, unwarranted claims, unacceptable interpretations, and personal views… Publications that have not undergone peer review are likely to be regarded with suspicion by scholars and professionals….”

Grey literature on the other hand is:
“Grey literature stands for manifold document types produced on all levels of government, academics, business and industry in print and electronic formats that are protected by intellectual property rights, of sufficient quality to be collected and preserved by library holdings or institutional repositories, but not controlled by commercial publishers i.e., where publishing is not the primary activity of the producing body”

You can evaluate different sources in different ways: 

Journal Articles
Articles you find in scientific journals have been reviewed by an editorial board which appraises the articles they receive and determines whether the quality is good enough to publish or not. If there are problems with the research in a submitted article it is rejected. Many journals also use a peer-review process to evaluate articles. Colleagues from other institutions working within the same field evaluate the article and may suggest changes, clarification or additional research before an article is published.

Most of the journals indexed in subject databases such as PubMed, Embase and Web of Science are peer-reviewed. You can always check the journal’s website to see if it is peer-reviewed, and see how their articles have been reviewed.


Consider who has published the book(s) you are considering using in your thesis. Is it from a well-renowned scientific book publisher such as Elsevier, Springer, Karger, etc. whose primary audience is the academic and scientific community? Or is it from a publisher who mainly publishes popular literature written for a general audience?

Internet Sources
Special care should be given when using sources you have found on the internet, as basically anybody can publish anything there. Ask as the very first: Who is responsible for the website? Is it a non-profit or commercial organisation or firm?

The domain name gives you an idea of what kind of institution or entity which is associated with the website:

.com : commercial products or commercially sponsored sites
.edu : American educational institution
.int : organisations established by international treaties or international databases
.gov : American government resources
.org : organisations 

You can limit your search to these domains by using Google’s “site: function”. If you search for “AIDS site:.gov” you have limited your search to looking for web pages about AIDS hosted by the US government.

You can also evaluate the website by asking:

  • What is the intent of the website? To sell, inform, convince or entertain?
  • Is there a hidden agenda which you don’t notice at first glance?
  • Is the content biased or objective?

If your searches have yielded several hundred results, you are probably wondering how you can select a manageable amount of sources for your thesis in an efficient way. Learn how to choose the most relevant search results in the following.

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