There's obvious answers, like Lord of the Rings. Other popular series like Twilight, Harry Potter, etc. Sherlock Holmes books, or James Bond 007.

I lean towards more science stuff, so for fiction The Forever War, by Joe Haldeman. Foundation by Asimov. Clarke's 2001.

Going to the past, I'd take a comprehensive physics textbook. And just to put some style in it, I'd grab The Feynman Lectures.

I'd imagine that going "into the future" would make the question irrelevant, as you'd have access to all books anyways. Maybe something that captures what life was like, To Kill a Mockingbird. Adventures of Huckleberry Finn.