Pro EJB 3: Java Persistence API (Expert's Voice in Java)
From the reviews:"An introduction to the new Java Persistence application programming interfaces (APIs), this book serves not only as a tutorial on how to use them, but also as a basic reference text. … The book is very well written, and the technical material is presented clearly without excessive detail. … this is an excellent textbook." (M. S. Joy, ACM Computing Reviews, Vol. 49 (3), March, 2008)