Check out example codes for "you must add a reference to assembly 'System.Core, Version=4.0.0.0, Culture=neutral". It will help you in understanding the concepts better.

Code Example 1

//place this in the web.config file
<add assembly="System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>

<add assembly="System.Data.DataSetExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>

<add assembly="System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>

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