Ritter, Peter
Drei Stücke | für | Flöte, viola da Gamba und | Horn | Componirt v. P. Ritter. | Autograph, in D major
US-Wc ML 96.R5 E14 (autograph)
Although the part clearly calls for "Viola da Gampa", there is some doubt as to whether the part is for viola d'amore or baryton, judging by the tuning required and the presence of left-hand pizzicati.
Richard Sutcliffe, Retuning the viola da gamba in the late eighteenth and early nineteenth centuries, in Repertoire, Instrumente und Bauweise der Viola da gamba : XXXVIII. Wissenschaftliche Arbeitstagung und 31. Musikinstrumentenbau-Symposium, Michaelstein, 19. bis 21. November 2010, Augsburg, Wissner, 2016
, pp. 214-215