The first book I read about dissociation was "Stranger in The Mirror" by Dr Marlene Steinberg. It opened my mind and my eyes.

"The Body Keeps the Score" by Dr Bessel van der Kolk has become my "this is what happened to me" book. I would recommend it to anyone who deals with dissociative issues and trauma.

"Waking the Tiger" by Peter A. Levine is the book I am currently reading. It's also a very helpful book for me. To me it explains the fight/flight/freeze in very easy to understand language.