Hayes, S. C. (2019). A liberated mind: How to pivot toward what matters. New York: Penguin/Avery. This is a trade book, released in August 2019. It is in part a fairly comprehensive review of the CBS research program from its inception to 2018.
Hooper, N., & Larsson, A. (2015) The research Journey of Acceptance and Commitment Therapy (ACT). London:Palgrave Macmillan
http://www.palgrave.com/gp/book/9781137440150#otherversion=9781137440167