What are the definitive books on the AR and why?
I doubt there is a definittive book written on the AR platform. Theres better info on this forum than you will find in any book. IMHO.
Heijutsu=Jujitsuka?
Heijutsu = The Art of Warfare
Yes I know but most who use this term are affiliated with some form of budo.
Iaido, Aikido, Wing Chun, Kali