C#设计模式学习资料--观察者模式

http://www.cnblogs.com/promise-7/archive/2012/05/14/2500759.html

http://www.cnblogs.com/zhenyulu/articles/73723.html

http://www.cnblogs.com/BillChen/archive/2008/03/26/1122908.html

http://www.jb51.net/article/31665.htm