In general, a "scholarly" source is one that is written or edited by a "scholar" -- that is, a person who has earned a graduate degree in the field they are writing about. Having such a degree (usually a Ph.D.; synonym: a doctorate) means the person has had to prove that they have studied the field extensively and have mastered it well enough to be considered an expert in it. This doesn't mean that the person's interpretation of their field is beyond question or debate; rather, it means that they at least know enough about the field to have an INFORMED interpretation (in other words, one that others ought at least to consider).
People who are professors at a college or university may safely be considered "scholars" because they have usually earned a graduate degree in their field of knowledge.
People who publish books can usually be considered "scholars" because most publishers only publish books that have been reviewed by two or more experts in a field, which means that at least a couple of experts have agreed that the author of the book is well enough informed about their chosen subject matter to be considered a scholar. Hence, a book may usually be considered a "scholarly" source.
Articles in a journal published by a college or university can be considered "scholarly" because "scholars" have approved those articles.
Articles in a journal published by a scholarly group such as the American Medical Association or the American Bar Association or the Modern Language Association can be considered "scholarly" because, once again, such articles have been reviewed by experts in the field.
If you aren't sure whether or not the group that publishes a journal is "scholarly" or not (for instance, maybe you've never heard of the Modern Language Association and so don't know that it is the association of college and university English professors), you can look at the section in the journal where the list of editors is given. Scholarly journals usually list not only the editors' names but also their academic credentials (what degrees they have earned, or where they are a professor). If a journal offers no such list, then chances are it is NOT a scholarly journal because if it were, it would list the names and credentials of its scholars. You can find this information by looking at a hard copy of the journal or by visiting the journal's webpage and searching for its list of editors.
If you run across a random article on the Internet, you need to ask at least two questions:
I hope this explanation helps you determine whether or not your sources are scholarly. Again--if you have a question about a source, ask a librarian about it (preferably either Ryan Roy or Tom Henderson), or, if they are not available, bring it to me.
Darby Ray, Ph.D.