What makes a book or a book chapter scholarly?
Scholarly books, whether written by one author or contributed to by many authors, share some common traits. They are written by experts-- researchers, professionals, professors, and other scholars-- to present research, analyze trends, and otherwise communicate with their peers in the same field.
They are most often published by an academic press, including university or college presses as well as others:
The author or authors’ credentials might be listed and are relevant to the topic of the book:
From Functional Magnetic Resonance Imaging Processing by Xingfeng Li