If you search the book on Amazon.com, you will notice there are two books listed. Originally, I had intended to separate all the books (for a total of eighteen books). However, after going through the process of uploading the books and determining pricing, I felt like it made a lot more sense to combine three together into one volume. I was able to set a lower price per book by combining them in this fashion. I had wanted to delete Book I; however, it seems as if it will always be visible even if I delete it (will be listed as 'out of print'). Considering that I thought this would be confusing to see the first book listed as 'unavailable', I decided to make it available since it was going to be visible whether or not it was active. Hope this post clarifies things a bit.