S., My twins went through the exact same thing, which was made worse by the fact that prior to having them and becoming a stay at home mom, I spent a very successful career in book publishing! I completely know how you feel--it was truly the one thing my babies did that threw me over the edge, to the point that I actually asked my doctor if it was abnormal, and whether paper/cardboard could cause a bowel obstruction! The good and bad news is, there isn't a whole lot you can do about it. It will pass with time, it's just part of the teething/mouthing process (and no, mine didn't want teething rings or toys, they just wanted to bite and RIP the spines of their books, then eat the paper).
My twins are 20 months old now, and I can safely say they read their books more often than they eat them--and that's with their eye teeth poking through and sending them into fits of pain. The best advice I can give you for coping is to put the books in something that has a lid--we used a coffee table-type cube. Open the cube and say, let's read our books, not eat them. When they start to chew, tell them again, and then tell them they have two more tries. When they get to three times, they're out, mainly because you will be at your edge and it will be better for everyone to just put the books away and try again later. Hope this helps. L. M.