Currently in no particular order. Most of these are kind of ancient.
Where's all the modern documentation? So much of what I've turned up searching is other folks complaining about having few options beyond reading source code.
The OREILLY books, while dated, seem to be some of the best available. Note that these can be read with a 7-day trial. Do this! At least get through the introduction section and first chapter of each to see if it's what you're after.