Programming Clojure 2nd Edition

From http://pragprog.com/book/shcloj2/programming-clojure

If you want to keep up with the significant changes in this important language, you need the second edition of Programming Clojure. Stu and Aaron describe the modifications to the numerics system in Clojure 1.3, explain new Clojure concepts such as Protocols and Datatypes, and teach you how to think in Clojure.