As stated above, the problem with books on the subject is that they are trying to hit a moving target. So even the most recent book on computer hardware was probably researched a year ago.
The internet is chock full of good current (and not so current) information and advice and it's free to get your info from sites like THG, so while it's not strictly answering the question you asked, my advice is not to bother with a book - even if you could find one on overclocking. Just don't rely on one source of info. Head on over to the overclockers forum, or anand tech and have a read when you are done here. Even wiki is worth a read on the subject.