Another good series from CBT Nuggets. It has seemed hard at beginning, but as you progress and come to the end, it all makes a perfect sense and one can learn a lot already. i would definitely recommend it!
2. Oracle Essentials 4th Edition by Rick Grenwald
Great book for starters in administration, explaining most of the capabilities of the Oracle DB (still have not read it)
3. RMAN Recipes for Oracle Database 11G
Great book with exact recipes for the things you need. If you need to do for example incremental backup you go to that art of the book and see how it is done (How not read it yet)