As the above post says, there isn't one standard book for
EJB 3 that will help you for the exam.
Our lives were wasy with the previous SCBCD exam version as we had the Head First book. But now we need to refer to a couple of them and also have a look at the specs.
Apart from the books mentioned above and the specs, use MK's notes as well. They come handy for SCBCD 5 preparation and are a good supplement to the specs.