Appropriate Books.

If a particular parent has a problem with a book or textbook, I think they should have the right or possibility of requesting for their child to read a different book. If one parent has a problem, but another doesn't, I don't think they should have the right to take away a book for one students, just because you don't want you child to read it.
Some parents don't mind if their children read an "inappropriate" book. The parents would have no problem because their kids are exploring a variety of books that they can read. If you don't want your child reading certain book, tell them that. Don't make schools limit their library for certain books so some kids that have no problem reading those sort of books can't read them.
Schools should have a system so that if you would not like your child to red a certain book or books, if they don't already. This would be ideal so that you could not limit the reading potentials of other students in the school.