The best book on the topic, AFAIC, is Judith Herman's Trauma and Recovery. I also really like Lenore Terr's Too Scared to Cry -- a fascinating study of what happened to a group of children whose schoolbus was highjacked and buried underground. The insights are remarkable.

There's also Scaer's The Body Bears the Burden. Brilliant book, but sometimes just too medically dense for the lay reader. Same problem with van der Kolk.