Also, I've mentioned this in another thread, but the actual Book of Corrections written by Ryu Seongryong is available as a paperback book in an English translation. It was published by Cal-Berkley's Institute of Asian Studies in 2002. Go to bookfinder.com and you can get a used copy for under $20 or a new one for $24. I got a copy after IYSS ended and thoroughly enjoyed reading it. Excellent translation, and the text itself was very easy to read. Should be a great companion to watching this series.