Before you evaluate a source, it helps to know what kind of information source you're looking at. Talk with your advisor about the types of sources you should seek and avoid. Keep in mind that sources may not fall neatly into a single category.
Scholarly, Peer-Reviewed Articles
Scholarly, peer-reviewed articles -- sometimes called refereed articles, primary research sources, and original research -- are written by and for scholarly experts and published in scholarly journals. Researchers who wish to publish scholarly articles must endure a rigorous editorial procedure called peer-review. Math and science undergrads are expected to ground their research (or the literature section of their research) in at least one scholarly article. (Humanities and social sciences undergrads are expected to use more scholarly texts in their research.)
Popular News Articles
Popular articles tend to be shorter than research-based scholarly articles, are written for the general public, typically written by journalists (although scholarly experts are sometimes the authors), and published in newspapers and magazines. While popular treatments of scholarly studies can oversimplify research, they can assist readers with otherwise jargon-heavy studies.
Trade Magazine Articles
Trade articles -- such as those published by the AIP, MAA, and IEEE -- exist between popular and scholarly sources. Readers are expected to have some background on a topic, but not to the degree that scholarly specialists will have. Such readers include enthusiasts without formal education in an area, and those with bachelors degrees who never pursued a graduate degree in their field. Math and science undergrads may find trade magazines targeted to educators helpful complements to scholarly treatments.
Review Articles
Review articles, written by and for scholarly experts seek to critically synthesize existing research on a topic. They are particularly valued in areas where a lot of research is being done at a rapid pace such as in medicine and physics. Not to be confused with book or film reviews, review articles are sometimes referred to as secondary research sources having drawn from existing studies. Nevertheless, review articles--such as those published in APS Physical Review journals--are highly regarded with some undergoing peer-review; the journal or publisher website should explain any editorial policies.
Books (Scholarly, Popular, Trade)
Books bring together a large segment of what is known on a topic, and can help researchers contextualize an idea or experiment within a larger body of knowledge. Books can be written for different audiences and for different purposes including encyclopedias that seek to explain complex topics to non-experts, and textbooks that aim to educate.
Pre-prints & Post-prints
Pre-prints and post-prints refer to scholarly literature before (pre-) peer-review and after (post-) peer-review, and are considered unofficial versions of formally published scholarship. You'll find these in author websites or repositories like arXiv and may look like a regular Word document before they've been formatted by a publisher. Although pre-prints and post-prints may be more readily available on the internet, whenever possible use and cite official, published documents in your research.
Conference Papers & Proceedings
Conference papers and proceedings are typically written by and for scholarly experts and can provide a glimpse into cutting edge research. Sometimes scholars will present at conferences on their research before or soon after a study has been published. Sometimes these presentations are collected and published in the form of a conference paper (individual) or proceedings (collection of conference paper). Some papers/proceedings undergo peer-review which should be explained on the conference or publisher website.
White Papers
White papers are often authored by government agencies (e.g., NASA), organizational bodies (e.g., ACM), nonprofits (e.g, Sierra Club), companies (e.g., Esri), or their representatives, and written for audiences external to themselves. They often take the form of reports or other documentation that seeks to explain a policy or the basis of a position. White papers do not undergo a formal peer-review process.
Dissertations & Theses
Dissertations and theses are extensive research projects undertaken by students working toward an undergraduate or masters degree (theses) or doctoral degree (dissertation). Since advisors and committee members thoroughly review these works, the process differs significantly from that of peer-review. Dissertations and theses are increasingly available online through institutional repositories like InSPIRe.
