It must be noted that some of the books named above are no longer in print but if you can track them down it will be time and effort well spent. You will also notice that the books are all Judo manuals and that no Ju-Jitsu books are recommended. The reason for this is that there is no world standard for Ju-Jitsu as there is in the case of Judo. So in order to avoid confusion we recommend that you spend some time studying the Gaven-ryu System before reading books covering other systems that could lead to bad habits and technique.