- The Oster collection [microform] : papers of Heinrich Schenker /
- File 38: Draft Material for Der Freie Satz and Early Articles /
- Part 5 /
- Recto: "Von der Zusammenfassung der Variationen". Text in Jeanette Schenker's hand with emendations by Schenker, labeled page 276, with sketches for graphs of Ludwig van Beethoven, Sonata, Op. 26, A Flat Major, Theme; and [probably] Ludwig van Beethoven,