Having successfully taken a couple ASQ exams including SSBB, the Quality Council of Indiana books are what everybody should use. They're not great to TEACH you the material but if you need a rapid resource during the exam they are perfecty designed with a great index and a level of detail exactly matched to the exams. You'll need to pull out the blue answer sheets.
I've brought along other books to exams (Juran, Montgomery, etc.) but 95+% of the things I've ever looked up were in the corresponding CQI book.
Good luck,
David