Piano Sonata in C major, D 279 (Schubert)

The Piano Sonata in C major, 279 is a piano sonata composed by Franz Schubert in September 1815. The sonata has three movements and is regarded as incomplete for lacking a fourth movement. D. 346, an unfinished Allegretto in C major, has been suggested as its final movement.
Movements.
The piano sonata D. 279, composed in September 1815, has three completed movements:
Since 1928 several scholars, the first being Walter Rehberg, have suggested D. 346 to be the finale of the sonata D. 279:
An abandoned start of a Rondo in C major, D. 309A (mentioned p. 173 in the 1978 version of the Deutsch catalogue however without a catalogue number being assigned to it at the time, so in several publications mentioned as D deest), dated 16 October 1815, is another candidate for what Schubert might have intended as last movement for this sonata.
Score.
There were no publications of this work before the Breitkopf & Härtel Alte Gesammtausgabe (AGA) edition of the end of the 19th Century.
Manuscripts.
The autograph of D. 279 is titled Sonate I, and has September 1815 indicated as time of composition. The autograph of D. 346 has no date. Both autographs are in the city library of Vienna, and can be consulted online via the Schubert-"Autographs" website.
The autograph of D. 277A has disappeared, but there is a manuscript copy by Eusebius Mandyczewski. The autograph of the D. 309A fragment has only six bars, and was later completely crossed out by Schubert. This autograph, above the second autograph version of D. 310, is in the Austrian National Library, and has been made available on-line.
First publication.
D. 279 was first published in 1888 as No. 2 of the Piano Sonatas volume (Series X) of the "Kritisch durchgesehene Gesammtausgabe". The second volume of the Supplement (Series XXI) contained the D. 346 fragment. D.277A was first published by Otto Erich Deutsch in 1925.
Urtext Editions.
Two Urtext editions were published in 1997: Paul Badura-Skoda (Henle) completes the Sonata in C major D. 279 with the Allegretto D. 346, and gives D. 277A in an appendix. The other publication of the same year is by Martino Tirimo (Wiener Urtext).
Neue Schubert-Ausgabe (NSA).
The New Schubert Edition has D. 279 in VII/2/1. The Rondo D. 309A fragment is given in an appendix of that publication. D. 277A and D. 346 are contained in VII/2/4
Performances.
The work, including the D. 346 finale, takes approximately 20 minutes to perform.
Performances of the sonata with the D. 346 Allegretto as finale include the December 2000 recording played by Tamara Rumiantsev. Bart Berman recorded a completion of the D. 279 sonata.