I'm researching vodka and potatoes in a project with Karlsson's Vodka. In a previous post I wrote up a few books I sourced on the history of potatoes. Below are some books that were useful in researching the history of vodka.
Vodka: A Global History by Patricia Herlihy
Classic Vodka by Nicholas Faith and Ian Wisniewski
The Vodka Companion: A Connoisseur's Guide by Desmond Begg
Vodka Politics by Mark Lawrence Schrad
Vodka Distilled by Tony Abou-Ganim and Elizabeth Faulkner
The King of Vodka by Linda Himelstein
I'd say the most useful of them have been the books by Faith and Begg, followed by Herlihy and Faulkner (who did a nice summary of Faith and Begg).