Many of my friends recommend "The Explosive Child," by Dr. Ross Green:http://www.fishpond.com.au/Books/Explosive...e/9780061906190
On a related note, and because my antenna is always up, I know that you've mentioned concerns in the past about your son's behavior. One thing you might consider, if you haven't done this already, is getting a developmental assessment done. You can either go through a developmental paed or through your local area health service (you will need to get referred by your GP & one other child professional). My understanding is that the local health service assessments are comprehensive & can also help link to other services, if needed.
Of course, preschoolers can be naturally challenging creatures even without underlying "issues" -- but in case there are issues contributing to your son's behavior, it is much better to get a good grip on them before the child starts school.