The most popular book is the Allen Carr’s one: Easy way to quit smoking. By the way, if you quit some days ago, the QuitNow! team would recommend that avoid this book. It says that you can smoke while reading the book, but the people we interviewed relapsed. We could say that it’s a book to warm up before actually quitting.
The second most popular book is How to quit smoking without feeling like sh*t. It talks about quitting gradually instead of by cold turkey. Remember that the W.H.O. encourages you to quit smoking by cold turkey because studies demonstrated it’s easier and has fewer relapses.
The last one we would recommend is the miniature edition of Quit: read this book and quit smoking. It also says that you should smoking gradually, that the W.H.O. disagrees, but it has a good concept: it has the same size as a cigarettes pack. So you can literally replace your old pack with this book.