For the Love of Hops by Stan Hieronymus. Available in print and Kindle versions. Part of the Brewing Elements Series – Yeast, Hops, Malt, Water.
About; “Stan Hieronymus expertly explains the nature of hops, their origins, hop quality and utilization–and even devotes an entire chapter to dry hopping. For the Love of Hops also includes a reference catalog of more than 100 varieties and their characteristics.”
For The Love of Hops: The Practical Guide to Aroma, Bitterness and the Culture of Hops (Brewing Elements)
Also: 5 Recent Hop Finds || The Homebrewer’s Library – Selection of Homebrewing and Craft Beer Books