Ser in D, K.320 'Posthorn-Ser', Concertante: Andante grazioso-Ca • Whose Song?

Ser in D, K.320 'Posthorn-Ser', Concertante: Andante grazioso-Ca
is a song by
Mozart
it was released on
Posthorn Serenade: Marches KV 335 [Nikolaus Harnoncourt, Dresden