title: I am getting "defined in an assembly that is not referenced" errors when building my c# project, how to solve it?
body: <p>I have already have references to System and System.Data. </p>
  
  <blockquote>
    <p>1.The type 'System.ComponentModel.IListSource' is defined in an assembly that is not referenced. You must add a reference to assembly
    'System, Version=2.0.0.0, Culture=neutral,
    PublicKeyToken=b77a5c561934e089'.</p>
    
    <p>2.The type 'System.Data.Common.DbDataReader' is defined in an assembly that is not referenced. You must add a reference to assembly
    'System.Data, Version=2.0.0.0, Culture=neutral,
    PublicKeyToken=b77a5c561934e089'.</p>
    
    <p>3.The type 'System.Data.IDataRecord' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data,
    Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.</p>
    
    <p>4.The type 'System.Data.Common.DbConnection' is defined in an assembly that is not referenced. You must add a reference to assembly
    'System.Data, Version=2.0.0.0, Culture=neutral,
    PublicKeyToken=b77a5c561934e089'.</p>
  </blockquote>
  
  <p>I have already have references to System and System.Data.</p>