ITIL V3 Core Reading

Here is a list of the core volumes that accompany the ITIL V3 courses:

ITIL Service Design 
ITIL Service Transition 
ITIL Service Operation 
ITIL Service Strategy 
ITIL Continual Service Improvement 
ITIL Lifecycle Publication Suite - All 5 core volumes in one package

Each of the ITIL V3 course pages details which of the core volumes you should read.