Use the book only for the questions. If you have already bought it that is, otherwise don't waste your $$. Like the others say, it is FULL of mistakes. Have a look at what he has to say about the HF req'd freq at night for another fine example.
The Ionosphere
increases in altitude at night due to a lack of things like solar winds!!
Don't buy these books to get the "answers" for an interview, because you will be shot down when they ask for more info.
You
need a good understanding of the subject, not just a memorized quote from a dodgy book.