The best source I've found for the Koryu no Kata outside of my instructor is a book called "Tomiki Aikido" by Lee Ah Loi. Its a small blue book and can be found on Amazon.com. It contains Nage No Kata as well as all six Koryu no Katas. It is a good book if you already have an understanding of the techniques, however trying to learn the techniques directly from the book can be problematic without someone to explain the fine points. Be forewarned, it does have some errors in it such as saying nage to step with the left foot, but the photo showing nage stepping with the right etc. But the order is correct and it has all the techniques.