Ser in D, K.320 'Posthorn-Ser': Menuetto-Trio I-Trio II-Coda • Whose Song?

Ser in D, K.320 'Posthorn-Ser': Menuetto-Trio I-Trio II-Coda
is a song by
Mozart
it was released on
Posthorn Serenade: Marches KV 335 [Nikolaus Harnoncourt, Dresden