title: 'ObservableCollection' could not be found even when using 'System.Collections.ObjectModel'
body: <p><code>System.Collections.ObjectModel</code> is included. Visual studio 2012 still says <code>Type or namespace name 'ObservableCollection' could not be found.</code></p>
  
  <p>Similar to <a href="https://stackoverflow.com/questions/6685448/the-type-or-namespace-name-observablecollection-could-not-be-found">this question</a></p>
  
  <p>Code:</p>
  
  <pre><code>class ObservableClass : ObservableCollection&lt;OtherClass&gt;
  {
  }
  </code></pre>
  
  <p>EDIT: This is .NET Framework 3.5 and is a console application</p>