This short video explain the terms scholarly/academic and peer-reviewed (or refereed) and how to identify whether a book would be considered "scholarly.
If you found a journal article via a list of works cited, a reference on the internet at large or via Google Scholar, it may not be clear whether the article is from a peer-reviewed journal.
You can use the directory below (Ulrich's Web) to check whether the journal the article is published in is a peer-reviewed journal or not.
You can also enter the title of the article into LibrarySearch and if turns up there, if it's from a peer-reviewed journal, it should have a "peer-reviewed" label indicating this.
NOTE: The "peer review" limiter in LibrarySearch and other databases though only applies to journal articles because it's a tracked and tagged feature and that's not a standardized (metadata) label for books.
The majority of the non-fiction books in the E.J. Pratt and all of the University of Toronto Libraries tend to be "scholarly publications". Books and chapters in anthologies would be subject to a form of "peer review" by an editorial committee, which is typically made up of fellow academics in the same field or in broader or related subject areas/disciplines. For an edited collection of essays or "papers", look for the section called "Contributors" for short descriptions of the contributing authors' credentials or expertise. Sometimes this information is at the start or end of each piece (chapter, essay etc.)
If your assignment requires "scholarly" sources, it needs to be authored by someone who has studied and has academic credentials in the broader subject area.
When in doubt, ask your instructor or TA about a source that does not explicitly have characteristics of a cited source (writing or a communication that cites its sources and to be considered scholarly, typically the authors have a PhD or advanced degree in a related field, or are listed as Professors or Lecturers at a related department at a postsecondary institution).