title: How to add an assembly reference to a VS 2015 vNext .NET 4.x targeted Project
body: <p>Visual Studio 2015 supports multiple build targets in a vNext project so you can build for vNext CLR, vNext Core <strong>and</strong> any other .NET build targets.</p>
  
  <p>I understand that vNext project require that dependencies have to be referenced via NuGet packages, but how can I add assembly references to the non-vNext projects that might require GAC or other external dependencies?</p>
  
  <p>My References structure looks like this:</p>
  
  <ul>
  <li>.NET Framework 4.5   &lt;--- how do I get an GAC/assembly reference into this?</li>
  <li>ASP.NET 5.0</li>
  <li>ASP.NET Core 5.0</li>
  </ul>
  
  <p>Use case: I'm building a library that can work both on standard CLR and the new vNext CLRs, but the standard version requires access to System.Configuration. How do I get the reference of System.Configuration into the classic .NET 4.5 target?</p>