Best book on overlockers/sergers?

Hi ladies, Which book would you recommend on using an over locker/serger? I don't want one that has 'projects' to make, but I like a nice meaty read, so something comprehensive. I am a beginner though have been using my machine fairly well so far, for basic stuff. I can thread it OK. It's a Juki 634DE, though I don't know if thats of any relevance when buying a book. I've looked at the internet for tutorials though I prefer reading. Perhaps you don't think I need a book? Thank you in advance,Linda