Books that hide their true meaning due to censorship

I'm looking for good examples of books that are written in a somewhat coded way, because of censorship and oppression in the countries where they were published. So you would have to read between the lines to understand what was really meant. I read that this is something that happened in many countries of the former Eastern Bloc, but of course all parts of the world are welcome.

Edit: So I'm looking for books that were written

• under a censorial regime/government

• that are in disagreement with that government

• and which use codes/allegories where you need to read between the lines.

Not censored books in general, not allegories in general.