The Elements of Java Style, Al Vermeulen (Editor), Scott W. Ambler, Greg Bumgardner, Eldon Metz, Alan Vermeulen, Trevor Misfeldt, Jim Shur, and Patrick
Thompson (Cambridge University Press, 2000) http://www.amazon.com/exec/obidos/ASIN/0521777682/javaworld
Synchronization and the Java Memory Model. An excerpt from Doug Lea's book that focuses on the actual meaning of synchronized http://gee.cs.oswego.edu/dl/cpj/jmm.html
Alpha Architecture Reference Manual, Richard Sites (Digital Press, 1998). The section on correct use of the MB (memory barrier) instruction is a useful introduction
to the concept of memory barriers http://www.amazon.com/exec/obidos/ASIN/1555582028/javaworld
The Java Language Specification, Second Edition, Bill Joy, Guy Steele, James Gosling, and Gilad Bracha (Addison-Wesley, 2000). See Chapter 17 for the gory details of the
Java Memory Model http://www.amazon.com/exec/obidos/ASIN/0201310082/javaworld