I think of stuff like Luty who was challenged in the UK under the terrorism act for sharing books on improvised firearms, Ashley Dugan who was charged with "distributing explosives training to terrorists" and some of his youtube videos pulled for sharing the well known public domain synthesis of RDX explosives.

These are non-sexually-obscene informational speech yet the librarians and teachers don't actually want you looking at these banned media because they could actually be used to challenge the established order and system rather than just shuffling who is in power to possibly the guy the librarian likes.