I used only this book for switching exam. I read it for less than three weeks. I found a few minor errors in printing and a lot of bug on test software. some questions are multiple choices but you can select only one and you are rated as incorrect for these. Reference in software just point to chapter, neither page number nor paragraph been mentioned. Oh, I passed the exam with a score of 869 on 5/31/01 eventhough one third of questions were never learned from this book. I think I was lucky on my guess;-)