First of all, I wouldn't start with reading the specification. It is better to have some understanding of the material when you do. If you are going for just one book you should choose between the O reilly book or Ejb in action. In action seems to be the most popular choice here. I have the O reilly book. Very few people will be able to compare them both (because hardly anyone reads both) Both books cover all aspects of EJB, but not in enough detail. Honestly, passing the exam is going to be hard just reading one of these books. Pro EJB Java Persistence Architecture is THE guide on JPA. It will give you roughly enoug detail for the exam I think. However, the scope is limited to JPA, and you need to know EJB3 as well.
Conclusion: 1) Use one of the books you listed, whichever you prefer. 2) Use additional references (exam sims, MZ guide in links section, specs, etc)