That depends on which SCBCD you're preparing. If you're preparing for SCBCD 1.3, then Head First EJB is the answer. If you're preparing for SCBCD 5, there's no study guide for that yet. But the Enterprise JavaBeans (3rd edition) and Pro EJB 3: Java Persistence API are the books that you might want to take a look at.
SCJP 5.0, SCWCD 1.4, SCBCD 1.3, SCDJWS 1.4