Scholarly articles/journals - also known as peer-reviewed, these are published articles, written by experts in the field, that have gone through a process of submission, review, editing, and approval. They are found in scholarly journals.
(telltale signs: title, author credentials clearly stated, abstract, presentation and discussion of data, conclusion, future research considerations, list of cited references)
Books/Book chapters - academic books are, in general, long explorations of a given topic, written and compiled by experts, that have gone through a process of editing and revision.
(telltale signs: reputable or University publisher, author credentials and affiliations, focused and in-depth treatment of subject, cited references)