I can actually only find reference to two types of reading matter that were allowed to survive in the quick lecture that Beatty gives Montag about the history of society and how it naturally erased books and reading matter from its consciousness. As Montag is lying "sick" in bed, Beatty visits him and tells him and us the history of their world and how reading books has become such a crime in this society. Notice what he says regarding permissible reading material:
But the public, knowing what it wanted, spinning happily, let the comic books survive. And the three-dimensional sex magazines, of course.
So, we can see that the society allowed pornography and comic books to survive the cull of reading material, reflecting the intellectual depths to which they plummetted and the kind of society that we see presented in this novel: a society based on instant gratification of lusts and desires rather than serious, thoughtful, introspective meditation.