To ferret proof your bookshelves you may want to try doing what we did to
baby proof ours years ago: Stuff the books in so tightly they can't push
them out.  Also push them to the back of the shelf so they can't get behind
to shove them out.
 
I don't know if this will work with ferrets or not.  Ours generally don't
bother the books too often, though we occasionally have shelf-clearing
shelter ferrets.  Recently someone has taken to scattering several years
worth of Consumer Reports on the floor.  Perhaps they were looking to see
if raisins were rated anywhere.
 
Linda Iroff
The Raisin Retreat
North Coast Ferret Shelter West
Oberlin, OH
http://www.oberlin.edu/~liroff/ncfs.html
[Posted in FML issue 2435]