Schmitt, Aloys : Sinfonie-Quartett
| Aloys Schmitt an Louis Spohr in Kassel | Frankfurt am Main, Mittwoch 1. September 1852 | 1852090145 |
| Aloys Schmitt an Louis Spohr in Kassel | Frankfurt am Main, Mittwoch 12. August 1857 | 1857081245 |
| Aloys Schmitt an Louis Spohr in Kassel | Frankfurt am Main, Mittwoch 1. September 1852 | 1852090145 |
| Aloys Schmitt an Louis Spohr in Kassel | Frankfurt am Main, Mittwoch 12. August 1857 | 1857081245 |