A good reference book for that nagging doubt on English Grammar... ( )

As a copyeditor, I need not only to know the answers but also to back up the choices I make when editing a manuscript. In that regard I have found this book exceptionally helpful. The author was a copyeditor himself for many years, so he knows the kinds of difficulties I am likely to encounter, and he helps me make the best choice when I am on the horns of a grammatical or stylistic dilemma. I would recommend this book to anyone who cares deeply about writing well and using language to its best effect. ( )