As it is in the Things_to_bring
- books. Also those you no longer need/want. Non-technical preferred. This is supposed to be your vacation, after all. Any eBook-Reader is a good choice too.
There has been confirmed on twitter  that there will be a table in the Hackcenter for sharing your books you no longer need/want. So go oldskool, read a tree! And share their words with others.
DO COME BACK WHEN EVENT IS OVER TO BRING YOUR BOOKS BACK HOME IF NOONE TOOK THEM!