-.-
Dictionary.ContainsKey() confusion in C#
http://msdn.microsoft.com/en-us/library/7h9bszxx%28v=VS.80%29.aspx
http://bytes.com/topic/c-sharp/answers/266088-override-gethashcode
http://msdn.microsoft.com/en-us/library/xfhwa508%28v=VS.80%29.aspx
http://msdn.microsoft.com/en-us/library/kw5aaea4%28v=VS.80%29.aspx
Herb Sutter:
http://herbsutter.com/2008/01/01/gotw-88-a-candidate-for-the-most-important-const/