Below are some of my favourite books and websites on this topic. 

If you click the links you will be taken directly to the Amazon website where you can find more details about the book.

Young Minds - https://youngminds.org.uk/find-help/feelings-and-symptoms/self-harm/

Self-harm (youngminds.org.uk)

NSPCC - https://www.nspcc.org.uk/keeping-children-safe/childrens-mental-health/self-harm/  Preventing Child Self-Harm & Keep Them Safe | NSPCC 

NFA- https://www.nfa.co.uk/story/story_category/understanding-self-harming-behaviour-in-children/  Understanding Self-Harming Behaviour in Children (nfa.co.uk)

These recommended books are linked to Amazon UK and may generate a commission which goes towards the costs of running this site.