Until now, the standard reference work has been Bugei Ryuha Daijiten, which is in Japanese. In the 1970's Donn F Draeger produced a series of books and a magazine covering Classical Budo, Bujutsu and Gendai Budo. Sadly he died in 1982 with many of his projects unfinished. Although there are many able international researchers and writers on the subject, there has been nothing in the English language thus far so comprehensive as Dr Halls' work. An essential addition to the Library of both researcher and serious Martial Artist. It is also interesting to note the person to whom the book is respectfully dedicated.
This one is very good, but perhaps not aimed at the person with a casual interest in martial arts, but rather the person with a deeper interest and knowledge in both gendai (modern) and koryu (old school) budo and bujutsu. It will definitely sit as a reference work in my budo/bujutsu bookshelf.
Must HAVE ,for all people who are interested in martial arts specially for advanced practitioners of Japanese koryu !!! Lots of info and pictures on topics that you can can only find by reading another 100 books in old Japanese .