FIDE Rules On Reading DURING Game Are you allowed to read a book unrelated to chess during a FIDE rated classical tournament game? I myself have done this a few times whilst studying for exams, but was never sure if it was allowed or not. I am 2100 so no one ever mentioned it. I'm hoping someone can post a definite answer.
There are two sections of the FIDE Laws of Chess which are relevant.

11.3.2.1 During a game, a player is forbidden to have any electronic device not specifically approved by the arbiter in the playing venue.

and

11.5 It is forbidden to distract or annoy the opponent in any manner whatsoever. This includes unreasonable claims, unreasonable offers of a draw or the introduction of a source of noise into the playing area

Use of a Kindle or other electronic book is governed by the first. You will have to get the arbiter's permission to read such a device during the game (or even to have it in the playing area) and this is unlikely.
For a traditional book printed on regular paper you just need to do it in such a way that it does not disturb your opponent (i.e. don't rustle the pages, put the book down noisily, etc.) as covered by 11.5. Although you would be well advised to talk to the arbiter first to clear the fact that the book contains no chess related material.
I have seen this done during FIDE rated league matches with no problems but not in large tournaments.