If I remember right, they quite possibly may be found in the grand library among others, but they are most likely looked upon as curiousities, as very little Dementlieu citizens have ever experienced anything like the creatures described in the books.
They just see the things referred to in the books in their wax museum.
Even most Barovians live entire lives without ever seeing a monster. But they believe in them, nonetheless.
I think having the occassional book search by the vallaki guard could be fun, however, we'd have to figure out how to handle it, since nobody really icly carries everything that is on their person around.
There isn't a safe way to hide a book due to engine limitations, so they are lugged around in bags.