I think he was referring to the book about defeating the dark one, you know the one from the dream. I still like your theory at this point and time I am trying to grasp on to any hope I can find. I hate the idea that a baby can hate his father even before he is born, there is something completely wrong about this. If Morpheus does end up being their child I will be completely upset.
I took the book to be a reference to Her Handsome Hero, rather than the book about how to defeat the dark one from the vision, since Belle then proceeded to name her newborn son after the book’s protagonist, Gideon.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy