Who Are the Jehovah’s Witnesses?, by Clete Hux and Craig Branch.
Profile, by Jason Barker.
10 Important Questions For The Jehovah’s Witness Worldview, by J. Warner Wallace.
The Collapse of the Watchtower: A Presuppositional Critique of Watchtower Theology, by Fred Beall (Independently published, 2021).
Various articles from Watchman Fellowship, a Countercult organization.
Jehovah’s Witnesses: Their Claims, Doctrinal Changes, and Prophetic Speculation. What Does the Record Show?, by Edmund C. Gruss (Xulon Press).
Reasoning from the Scriptures with the Jehovah’s Witnesses, by Ron Rhodes (updated and expanded) (Harvest House).
Robert Bowman, Jr. has put together a research bibliography.