Q. What is a scholarly source?
A scholarly source is one written by one or more subject experts for an audience of other experts, researchers, or scholars.
Scholarly journals are largely where you will find scholarly sources. They are also known as academic journals. Many of the scholarly/academic journals also employ peer-review. Peer-review is a process where other subject experts review an article before it is published to make sure that it is up to standards. It gives these articles a higher level of reliability and credibility than those without peer-review.
Books can also be scholarly. You can determine if a book is scholarly by reading about the author, as well as examining the language of the text. Scholarly books are not written at a level for a general reader.