Robert Schumann, Album für die Jugend, Op. 68, Nr. 10: "Fröhlicher Landmann, von der Arbeit zurückkehrend" ("Happy Farmer, Returning from Work"), 37 seconds
Opening measures of Chopin's "wrong note" etude Op. 25 No. 5, demonstrating a humorous use of the minor second. The original work is public domain, image created by the uploader.
Großes Präludium in e-Moll von Nicolaus Bruhns. Source: http://www.free-scores.com/download-sheet-music.php?pdf=158, according to that page public domain. The instrument has been changed to church organ and the tempering to Werckmeister III.
Author: No machine-readable author provided. Phrood~commonswiki assumed (based on copyright claims).