My resources were UML Distilled (2nd edition) by Martin Fowler and Kendall Scott. I also used Applying UML and Patterns (2nd Edition) by Craig Larman. I found both books to be very useful but I found Craig Larman's book the most useful for the exam. Martin Fowler's book is very nice to read and provides a lot of concepts to use when designing your own code but I found most of these concepts to be "personal preference" and are not official UML terms. All in all, both are excellent resources. Good luck!