title: System.ComponentModel.IComponent ref. missing in MVC project. How to add it back?
body: <p>I am trying to remove the unused reference from VS 2012- MVC 4.0 project. 
  by mistakenly I have deleted all the references...</p>
  
  <p>I am trying to add it back again, I have also added all ref. back , but one of ref. is still missing, I am unable to find it in Reference Manager, not in Assemble neither in COM section.</p>
  
  <p>The error is ... </p>
  
  <blockquote>
    <p>The type 'System.ComponentModel.IComponent' is defined in an assembly
    that is not referenced. You must add a reference to assembly 'System,
    Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.</p>
  </blockquote>