A difficult task can be made easier when you have good tools. I wouldn’t go out and trim my roses without my leather gauntlets and secateurs. Line by Line by Claire Kehrwald Cook is an invaluable tool in the editing process. When I get to the editing phase of a piece, my dog-eared copy of Cook’s book is right at my elbow next to my coffee cup. My copy falls open to the chapter on punctuation because I still have issues with discretionary commas and need to reign in my use of the semicolon. Do you have reference books that are filled with post-its and underlining? Which are your favorites?