I have a book for the current 1Z0-047. I don't know if they still have the 9i exam.
The book is: OCA Oracle Database SQL Certified Expert Exam Guide. By O'Hearn. You can purchase on amazon.
I sat for the exam once and failed. It was the most difficult certification exam I have ever taken. There are a majority of questions that the multiple choice answers are exactly the same except for placement of parenthesis or the use of aliases or table names. I am scheduled to retake next month.
I have found the test exam sold with the book and the test exam sold by selftestsoftware.com are pretty similar in style to the questions on the real exam.
When you do things right, people won't be sure you've done anything at all.
Think of how stupid the average person is. And how half of them are stupider than that. But who reads this tiny ad?