So I've looked around to try to find some posts on this and there are many but none that address my specific question (that I could find). 

I am trying to add some DLL's in my project but few of them are coming from :

```
C:\Windows\Microsoft.NET\Framework\v3.5\XXX.YYY.dll

```

and what I expecting this should be coming from GAC. 

Please suggest me the best practice to reference the Dll's in Visual Studio.