i looked into syllabus of this certification. I guess Kathy Sierra book will be fine but not 100 % sure .
But I would appreciate if you can post your query in SCJP forum. There you can recieve better answrer for query.
Current forum (Certification results) is for only posting success achieved in various certificate exams.
subject: 1Z0-851: Java Standard Edition 6 Programmer Certified Professional Exam from Oracle