Books and Book Chapters

Should be scholarly or peer reviewed.
Webster's Third International Dictionary defines scholarly as:

1. concerned with academic study, especially research,
2. exhibiting the methods and attitudes of a scholar, and
3. having the manner and appearance of a scholar.

A scholarly book/chapter is substantive in content, authoritative, and professional. It is usually written for peers in a field, but it can be aimed at the general public if the purpose is to educate or provide expert guidance. Depending on scope and purpose, it may or may not include a bibliography, but the work itself is reflective of scholarship and is written to the discipline's professional and ethical standards.

A peer reviewed (aka "refereed" ) chapter or book has been submitted for review by several other scholars, experts, or academics for review and comment. These reviewers must agree that the content represents properly conducted original research or writing before it can be published.