Personally, I would thoroughly read the whole book.
If you go to the extent of writing it in your personal statement, interviewers could ask you about it and will expect you to have been really interested in it. Many people will reread any books they’ve mentioned in their application so they have a really good knowledge of it and fresh ideas.
If you really don’t want to do that, you could skim the whole book AND thoroughly read the section you’re interested in.