Not about DID specifically but for cPTSD I found the writings of Pete Walker and Judith Herman very illuminating.

Coping with Trauma-Related Dissociation by Suzette Boon

I don’t have DID, but parts work has been super helpful for me. Plus there’s an audiobook version, which has been great since I have a hard time focusing on reading. I’ve gotten a lot out of it so far

The CTAD Clinic on YouTube has excellent info on structural dissociation.