Vienna Gambit declined with d6 and Nc6
Gary Lane has written a nice article on ChessCafe on how to play aginst 3... d6 in the Vienna Gambit.
3... d5 is the recommended move for black in the Vienna Gambit. This is not easy to see over the board, and 3... d5 is often seen in practical play.
Lane promotes as his main line a simul game between R. J. Fischer and and T. Kumro from 1964.