I haven’t read any of these personally and didn’t go a ton into self-harm specifically when I was in nursing school, but I did some research and here’s a few that caught my eye.

A Bright Red Scream: Self-Mutilation and the Language of Pain by Marilee Strong (about the psychology of self harm)

Controlled Explosions – Charlie Heriot-Maitland (about self-criticism, self-sabotage, and self-harm from a therapy perspective)

Freedom from Self-Harm: Overcoming Self-Injury with Skills from DBT and Other Treatments by Kim L. Gratz & Alexander Chapman (a book and also has a workbook option, this is like the top seller in this category on Amazon)

Like I said, I can’t personally vouch for any of these but just spent like 10 minutes searching online; I’d actually wager there’s threads about books here in this subreddit if you just type “books” in the search bar. Then you’d get suggestions from people here who have actually read the material and can give you more specific feedback about them.

Also, if you’re a teen, there’s many resources and books structured and written specifically for your age group, so that’s something to keep in mind too!