Spank and the World Spanks With You! - Szczepankiewicz
My Life in the Shadow of the Don - Szczepankiewicz
Defend Dot Net, The Early Days - Szczepankiewicz
Biscuits Bri Thai and other Holiday Desserts from the Octagon - Szczepankiewicz
Seriously though, I would highly recommend anything by the following:
Loren Christensen Peyton Quinn Alain Burrese Marc MacYoung
And I agree with Bri Thai to read Geoff Thompson's work as well.
These would give you a good idea if what you're doing is really self defense.
The Incredible Spank