You might also become familiar (if you aren't already) with www.endabuse.org - the Family Violence Prevention Fund's website. This is a large organization that promotes research and education about domestic/intimate partner violence.

There is a lot of literature out there, but I'm sure you could find some niche for your book. This is a topic near and dear to my heart, and although I've never been in a physically violent relationship, I have done several years of crisis advocacy counseling and shelter work. If you'd like some other resources, feel free to contact me. (Although I'm about to move, and will lose my internet until Tuesday.)

Good luck,
Danielle