CBT books for kids?

I'm trying to learn more about CBT therapy for kids

Our psychologist recommended CBT therapy for him, but it's so hard getting appointments, and the cadence is poor.

Aside from going to therapy, I want to support the process, and help him when I can.

I tried looking for books or any other educational material, but didn't find anything so far.

Does someone know about the best way to learn and support your children who are undergoing this type of therapy?

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