This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The book has 95 puzzles! While it isn't a reference, it does contain one: Appendix A is a reasonably comprehensive list of the traps and pitfalls in the platform, cross-referenced to the puzzles and the relevant sections of the Java Language Specification, Effective Java, and other relevant references. The hope is that you can enjoy solving the puzzles, and then once you're done, return to Appendix A as a reference.
Click and Hack, the Type-it Brothers
Joshua Bloch <br />Author of <a href="http://www.amazon.com/exec/obidos/ASIN/0201310058/ref=ase_electricporkchop" target="_blank" rel="nofollow">Effective Java</a> and coauthor of <a href="http://www.amazon.com/exec/obidos/ASIN/032133678X/ref=ase_electricporkchop" target="_blank" rel="nofollow">Java Puzzlers</a>