I referenced all three and they were helpfull, yet there is no magic formula that beats getting your general drug catagories down (ACE Inhibitors, NASIDs, etc.) and just plain study study study til you half way know the material.  You really have to just do it for in the end there are those who do and those who do not.  So if you don't already, work on getting your general drug classes figured out and then move to the popular drugs within each specific catagory.  There are piles of great books on the subject, but they have to be read first.  There is a great deal of freeware on the internet as well (Epocrates is a nice one).  I made a lot of flash cards of different drugs as well which I would study at red lights when driving to work or school.

Cheers, good luck, and study - Tim, R.N.