One suggestion.. if you're going to study ORM, why don't you study JPA instead? JPA is the official specification for ORM in Java. Doesn't matter which implementation you use (Hibernate or Oracle Toplink or Apache OpenJPA) the code will be always the same. (at least in theory)
A good book for JPA is: Pro EJB 3 - Java Persistence API - (Apress)
The Bauer book, Java Persistence with Hibernate, is the reference on Hibernate. It tells you everything you need to know, in very precise detail, covering everything you could possibly imagine about Hibernate. It's the standard, and everyone using Hibernate should have it.
I might not recommend that book for learning Hibernate though. It's like learning to drive a car by first learning every little bit of detail about the internal combustion engine. Sure, it's great information to know, but it might be overload at the start.
I wrote Hibernate Made Easy to help people get started with Hibernate. I'd obviously recommend that, but of course, I'm biased. In all fairness to other authors, I'd also suggest Hibernate: A Developers Notebook as a great place to start learning Hibernate as well.
On my website, I have a number of simple tutorials designed to help you get started. Check them out! See how quickly you pick up the concepts, and then decide which book you think will help you the most.
Hi Poonam, If you are new to Hibernate and want use Hibernate in professional level, The best book is "Professional Hibernate" - Eric Pugh and Joseph D. Gradecki. When I was new, I refer 3-4 book and I found 'Prof. Hibernate' is very use full book for development point of view.