Visual Studio - Restricted Add Reference tab

I came across a solution with 3 projects (class libraries). When I select "Add Reference" option for 2 of these project, normal add reference popup appears with all options. However, when I try "Add Re开发者_运维百科ference" for 3rd class library project, it just gives me 2 options - SQL Server tab and tab with only projects in solution. No browser button or COM tab or .NET framework tab. How this would have been done?