Many wonderful judo resources are available to supplement the personal instruction provided in the dojo. Books, videos, and the internet provide a wealth of information for judo players of all skill levels. Foremost among the books is Kodokan Judo, by Jigoro Kano. This book describes the throwing, grappling, and submission techniques of judo. A brief introduction to the judo katas is also included. Many other fine books are also available including the judo Masterclass series from Ippon Books. Each of these books concentrates on a single technique or type of technique and shows the technique and defenses.