Use of Yield keyword in C#

http://www.codeproject.com/Articles/575713/What-is-the-use-of-csharp-Yield-keyword

Page Life Cycle

http://sureshpydi.blogspot.in/2011/02/asp-page-lifecycle.html
http://www.c-sharpcorner.com/uploadfile/puranindia/understanding-the-page-life-cycle-of-an-Asp-Net-and-its-controls/