well, i don't know what you've read so far, but here are a few suggestions:
Dogs : A New Understanding of Canine Origin, Behavior and Evolution
Raymond & Lorna Coppinger, ISBN 0226115631
Culture Clash
Jean Donaldson, ISBN 1888047054
The Other End of the Leash
Patricia McConnell, ISBN 034544678X
On Talking Terms With Dogs : Calming Signals
Turid Rugaas, ISBN 0967479606