Especially as someone diagnosed with DID, I find this book very useful for us. Additional attachment styles beyond the known 4 are described here, which I find incredibly helpful because I feel that the additional ones are more relatable than the known ones.
This book covers a variety on DID and even on DDs (dissociative disorders) in general. So if anyone is in need of information on these, this provides some information on DDs as well. Also covered are the topics of ritual abuse, organized abuse, and mind control, which can be helpful and validating for some.