An excellent source book for clarifying basic queries and the more complex. It also encourages further research, I have often picked up the book to look something up and half an hour later have become so absorbed chasing words and phrases!
Also good as a reminder to keep you focused, I have several similar books but this is amongst the best.
The hard cover makes it more expensive but this is a bonus as it is a well produced book which should last and last. Other paperback books I have have fallen apart from moderate use.
A definite for the Christmas stocking or birthday list.