"A book on Quidditch rules?" Hermione said, again, because he'd asked her at least three times on the way out of the stadium if she knew what the rules were for this sort of thing. "I've got a copy of Quidditch Through the Ages," she offered, turning to one of the living room bookshelves as she shrugged out of her jacket and looking for the thin green book. "I think you left it here, actually."