For starters you can download the free documentation from
http://www.oracle.com/pls/db92/db92.docindex?remark=homepage To understand how the DB works I suggest
Concepts
http://www.oracle.com/pls/db92/db92.to_pdf?pathname=server.920%2Fa96524.pdf&remark=docindex (strictly speaking you won't need this for the exam - but for true mastery of Oracle this should be your starting point).
In addition to cover the actual exam topics you will want:
SQL Reference
http://www.oracle.com/pls/db92/db92.to_pdf?pathname=server.920%2Fa96540.pdf&remark=docindex PL/SQL User's Guide and Reference
http://www.oracle.com/pls/db92/db92.to_pdf?pathname=appdev.920%2Fa96624.pdf&remark=docindex Check the syllabus, you may also want the
Supplied PL/SQL Packages and Types Reference
http://www.oracle.com/pls/db92/db92.to_pdf?pathname=appdev.920%2Fa96612.pdf&remark=docindex To learn how to use the features I suggest
Application Developer's Guide - Fundamentals
http://www.oracle.com/pls/db92/db92.to_pdf?pathname=appdev.920%2Fa96590.pdf&remark=docindex If you prefer paper based books I suggest you buy Steve Feuerstein's
Oracle PL/SQL Programming
The 3rd edition (ISBN: 0596003811) covers up to Database 9ir2, the 4th edition (ISBN: 0596009771) covers 10gr2.
For SQL I used various editions of Oracle: The Complete Reference
I can't speak from personal experience but for a tutorial approach you may prefer
Mastering Oracle SQL and SQL*Plus
Lex de Haan
ISBN: 1590594487
The Amazon reviews look reasonable.
