Senjutsu to Ninjutsu

I was not overly impressed by this book. It sort of dwells on spiritual teachings of the yamabush mountain warriors but really what was being said was not over impressive. Many years ago Stephen k Hayes wrote a book called ninja realms of power. Mr Hayes really got into the yamabushi thing so even if it was written some years ago I would say that it is still current. If you seek the more spiritual side of ninjuts then perhaps get a copy for yourself but it may be better getting a book by Hayes