Peer-reviewed journal articles are usually considered the most reliable sources. Therefore, such sources are sought after for project work. But what is peer-review?
Peer-review is a quality process that articles in scholarly journals must undergo:
There are reliable sources besides peer-reviewed journal, for example, books and web pages.
Books of a general nature are not peer-reviewed. Academic books, such as textbooks, are in most instances written by experts in the pertinent field and are therefore considered reliable sources. Such books undergo a quality process at publishers where one or more editors manage the publication of the book and give recommendations on what can be improved. University presses, such as the University of Iceland Press, Oxford University Press, and Yale University Press, send book manuscripts of scholarly books to peer-reviewers (see for example peer-review process at Oxford University Press and Cambridge University Press), but the peer-review of books usually differs from that of articles in scholarly journals. It can also be difficult to find out whether individual books have been peer-reviewed, but as was previously mentioned, a certain quality process is in place at most university presses and other publishers of academic or scholarly books books.
Websites are not peer-reviewed sources and not all of them fall under the definition of being reliable sources. Websites hosted by public institutions should, however, in most instances qualify as reliable sources.
The following criteria are often used to assess the reliability of websites as sources:
Journal articles on the internet (found using search engines, such as Google or Google Scholar) may or may not be peer-reviewed. Try to find out in what journal the article in question has appeared. Examine the website of the journal (the company that publishes the journal), paying most attention to “Submission guidelines” or “Information for authors” where it is specified what quality process articles published in that particular journal must undergo. You can also search for the journal in question on our journal search page and see whether the journal is peer-reviewed or not.