Reference materials are resources that are intended to be fact-based, such as encyclopedias, atlases, and dictionaries. There are no overt opinions, interpretations, or analyses in a reference entry, only facts and sound information.
Below is a screenshot of the "social justice" entry in the Salem Press Encyclopedia, accessed through our library website.
Source: Salem Press Encyclopedia at http://search.ebscohost.com/login.aspx?direct=true&AuthType=shib&db=ers&AN=98402201&site=eds-live&custid=hcc
Academic or scholarly sources are written by scholars and experts in a particular field. Writers of these articles have a point of view or are making a claim, and they back their opinions/claims with cited works and evidence. These articles are sometimes research publications based on studies, and have sections like abstracts, methods, results, etc.
Academic/scholarly journals are collections of articles in one academic publication. They are generally serial publications, and the most authoritative ones are peer-reviewed. Other identifying parts of academic publications are in-text citations, references listed at the end, and author credentials (for instance, a PhD and/or affiliation with an educational institution).
Below is a screenshot of an academic research article from BMC Nursing in our library database. You can see that it is categorized specifically as a research article because it mentions being a study and has research components like background, method, and results. It also has the other previously listed parts of an academic article.
Trade publications are journals and magazines written for professionals in a certain field, focusing on current trends and issues. A trade publication could contain news and current events relevant to the professional field, ads, product reviews, etc. Unlike academic/scholarly journals, they do not contain original research; they are meant to be practical, not theoretical.
Below is a screenshot of an article about the recent effects of social justice on publishing from Publishers Weekly, a trade magazine targeted at publishers, librarians, booksellers, and literary agents.
Source: Publishers Weekly at http://search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=147170160&authtype=shib&site=ehost-live&custid=hcc
Popular magazines are periodical publications with articles and illustrations, but they are marketed towards the general public or people with certain interests that aren't necessarily academic or professional. They typically cover a particular subject or area of interest, like current events, history, cars, hobbies, fashion, etc.
Below is a screenshot of an article on social justice published in TIME Magazine. It's marketed to the public and written in such a way that a layman can read and comprehend the article.
Books can cover virtually any topic, fact or fiction. They can even fall under reference. They don't have just one appearance; they can be hardcover, paperback, and even eBooks. And they could be fiction and look like a narrative inside, be a reference book and look like a list, or be a textbook and look sectioned out with visuals and charts.
For research purposes, you will probably be looking for books on a particular topic to support an argument or thesis for an assignment. Books are useful when you're looking for lots of information on a topic, to put your topic in context with other important issues, and to find summaries of research to support an argument.
Below is a screenshot of the main page of an eBook about social justice on Salem Press, with a table of contents and a box to search within the book. (Many books in the library are available online as eBooks and can be found in the library catalog or in library eBook databases.) Below that is the front cover of a hardcover book about social justice and antiracism.
Source: Salem Press at https://online-salempress-com.eu1.proxy.openathens.net/toc.do?bookId=930&bookTitle=Critical%20Insights%3A%20Social%20Justice%20and%20American%20Literature&bookCategory=Literature