There are a few different works called Ständchen or Serenade. This one is no.4 from a collection of songs D.957 published shortly after the death of their composer Franz Schubert and called Schwanengesang (or Swan Song) by the publisher. The song is a popular one and many arrangements have been made for various instruments and combinations of instruments. The particular arrangement here is for Guitar and was written by the Austro-Hungarian composer/guitarist Johann Kaspar Mertz. In the arrangement the guitar plays both the accompaniment and melody, which later on becomes two melody lines with one imitating or echoing the other. The sheet music, midi file or mp3 file can be downloaded using the links in the left-hand menu. Below you can see a video of the sheet music, play the mp3 file and see the sheet music before downloading. Here is the original Song for Voice and Piano, an arrangement for Flute (or other instrument) and Piano, and an arrangement for Piano Solo.