Six duos, op. 9 for 2 violas - Prot, Félix J. 1747-1823 (Gems Music Publ., 2010)
"Urtext.". - Includes biographical notes
Duo no. 1 in E-flat major -- Duo no. 2 in C major -- Duo no. 3 in G major -- Duo no. 4 in A major -- Duo no. 5 in D major -- Duo no. 6 in F major