Confiscate the damn books and burn them.
And then use the terrorist prisoners as the subjects in wound ballistics testing. ......like the Strasbourg tests (except using goat-lovers instead of goats).
Why do we even allow them to have these items. How are these things being leaked from a super secure installation? Are we allowing these leaks? Are we being compromised by allowing the wrong people into speak with these prisoners? Do the commanders at this super secure installation understand that this type of information only hurts us and completely undermines any good.