1958/1959 - Beethoven - Piano Sonata No. 27 in E minor, Op. 90: II. Nicht zu geschwind und sehr singbar vorgetragen

Commercial (originally unissued) recording - These recordings were made in a commercial setting but were initially left unreleased by the record label, typically due to quality concerns, artist preference, or market considerations. Some were later rediscovered, often as test pressings or master tapes, and issued posthumously or by specialized labels.