Hi Dan,
In my opinion, hard copy books aren't as useful anymore. To start learning Squeak, if you have already downloaded the latest all-in-one, execute it, click the Help button on the top menu bar, select Terse Guide to Squeak, and study, trying statements out in a workspace. If some class looks interesting like a Dictionary, you may want to study it in detail to see how the data structure works - that got me a job once.
Unfortunately there is no equally clear help item covering the less essential categories, classes, and packages included with the latest Squeak or hidden around in other Squeak derivatives. But once you've learned one class like Dictionary in detail, it will be easier to explore others. And if you need something you can't find like a class to access a webcam, just ask.
Kirk Fraser