Brain lock. It's kind of older book but still good
I haven’t read it yet but I think the self compassion workbook for ocd by Kimberley quinlan will be amazing. I also really loved The mind workout by mark freeman as an introduction. And lily Bailey wrote a wonderful book about her own experience with pure o: it’s called because we are bad 💖
I highly recommend “Overcoming Unwanted Intrusive Thoughts” by Sally Winston and Martin Seif!
I have found the information on Rumination Focused-ERP by dr Michael Greenberg to be incredibly helpful. It’s not a book, still wanted to share incase it helps you too: https://drmichaeljgreenberg.com/targets-and-rationales-for-rf-erp-exposures/
Brain Lock, Twentieth Anniversary Edition Free Yourself from Obsessive-Compulsive Behavior by Jeffrey M. Schwartz And Understanding OCD Skills to Control the Conscience and Outsmart Obsessive Compulsive Disorder by Leslie Shapiro
“Turtles All the Way Down” by John Green and “The Man who Couldn’t Stop” by David Adam. The latter is more informative.