This is not an essential book for the aromatherapy novice.
I would not call it a quick reference at all. It contains some excellent information but to find it you will have to take some time to read the book. It covers a number of aromatherapy techniques which is very handy.
This is the first book on aromatherapy I ever bought, about 20 years ago. My copy is battered, there are notes in the whate spaces, post-its jut from the edges, and occasional oil spills mar the pages. I'm never giving it up. It's too valuable to me.