Below are some of links for further Adobe Illustrator CS4 materials:

Books -

Adobe Illustrator CS4 Classroom in a Book by the Adobe Creative Team		Illustrator CS4 Digital Classroom by the Aquent Creative Team
Adobe Illustrator CS4 How-Tos: 100 Essential Techniques by David Karlins		Illustrator CS4 for Dummies by Ted Alspach
Real World Adobe Illustrator CS4 by Mordy Golding		Brilliant Illustrator CS4 by Steve Johnson
Illustrator CS4 Bible by Ted Alspach		Adobe Illustrator CS4 on Demand by Steve Johnson and Perspection Inc.

Online training -

	Lynda.com tutorials for Illustrator CS4
		Length (hrs)
	Designing an Event Poster Hands-On Workshop	2.27
	Illustrator CS4 One-on-One: Fundamentals	16.75
	Illustrator CS4 for the Web	3
	Illustrator CS4 Essential Training	8.5
	Illustrator CS4 Getting Started	2
	Illustrator CS4 New Features	1.25