Oracle PL SQL Program Units Exam Guide by Steve Ohearn

The best book on Oracle I have read. Super clear and lucid explanation left no stone unturned. Let you understand PLSQL deeply.

But probably not suitable as a beginner book. You should read some beginners books first to get the vague but important concepts like putting on a outline of the sculpture. And then finally read this book will sharpen the outlines deeply and all the concept together and the everything clear and lucid, I call this kind of book the finalizer.

Read like this order to understand Oracle deeply or pass an OCA exam:

Head first SQL
Rampant Press Easy Oracle PL SQL Programming
Sams Teach yourself PLSQL in 21 days.
Oracle PL SQL Program Units Exam Guide (The finalizer)
Selftestsoftware

Oracle 11g for dummies
OCA Oracle 10g administration I study guide (The finalizer)
Selftestsoftware

Oracle SQL Tuning by Dan Tow

Oracle SQL: Jumpstart with Examples by Gavin JT Powell (F,L)
Oracle Performance Tuning for 10gR2 by Gavin JT Powell (F,L)
The art and science of Oracle Performance tuning (L)

Oracle SQL high performance tuning by Guy Harrison (W)  (The finalizer)