If you have Qlikview 11 for Developers I wouldn't buy Qlikview Scripting. There's little new in the latter that isn't covered as well or better in the former. But the Qlikview for Developers Cookbook I can recommend. And Learning QlikView Data Visualization is also a good book.
The one on Data Visualization is not an option because - afaIk, it might be different going forward, we have a new top_boss - we are bound in terms of visualization and layout by so many standards that we've pretty much maxed out our possibilities. I will, however, talk to my direct boss about that Cookbook.