Thanks so much for this. I am a writer on Medium and an editor both on Medium and elsewhere, but without books to claim. However, I just set up a Medium account for one of my clients who has written the finest accessible narrative poetry book I've ever been associated with . As soon as that book is on Amazon, I'll be taking advantage of this option. I have another client whose book has just been finished who also has a Medium account whom I will be notifying about this.