85% passed COSA. I prepared my COSA exam by using Bob's Airlaw book and online exam solely. The book is very helpful and very organised. The ASL office staff had no problem with the Airlaw abstract.
The Airlaw abstract is almost covered every aspect of CAO CAR and CASR. If anybody wants to prepare this exam, I will highly recommend this material, the only thing you need to do is read this one thoroughly.
I made a mind map to let myself get easier to recall the key point of each book and also don't forget to use the label and highlighter.