Interface vs. Abstract Class in C#
http://digcode.com/default.aspx?page=ed51cde3-d979-4daf-afae-fa6192562ea9&article=b9103da3-5c99-4831-8bf0-dc6bd810b480
Abstract Factory Design Pattern c#
http://www.geekdaily.net/2009/01/06/c-design-patterns-abstract-factory-pattern/
http://www.codeproject.com/KB/aspnet/SoftArchInter1.aspx
