most book stores , but you would have a better chance at say supercheap or a repco even a coventrys! They range in price from around $20-30 , if they dont have one ask them to order one in it is usually there the same day! You can get a Max Ellery's or a Gregory's , they are as good as the other except the ellery's has a more detailed wiring outlay than the gregory's!
Not sure about the ellery's having better wiring diagrams. I find the gregory's so much easier to follow. I have both here and usually go the gregory's for wiring.
What's the difference between understeer and oversteer? Understeer is when the driver is scared. Oversteer is when the passenger is scared.
I got my commodore/lexcen 1988-1993 vn-vp max ellerys book from repco for 40 bucks its got wiring diagrams and how to fix just about anything on your car .