These books actually are by J.K. Rowling. They're "Hogwarts Library books" she wrote for fundraising. The other 'authors' of the books are people she made up. For instance, Newt Scamander, who 'wrote' Fantastic Beasts and Where to Find Them, his grandson married Luna Lovegood and they had twin boys Lorcan and Lysander. These two books were mentioned in the Harry Potter series and JKR made them real because she's awesome :) Just thought you maybe would like to know :)