So I ran into a copyright issue with my current book. I'm an idiot, obviously. I have sent 4 kids into 25 books, of which 8 I would have to replace as they are not in public domain. I hope the day will come when art is free of protection, so we can simply share it. That is why none of my books are copyrighted and are published under the Creative Commons license. Here is a blog post on this glorious mistake.