Bethmann, Simon Moritz von
| Wilhelm Speyer an Louis Spohr in Kassel | Offenbach, Sonnabend 1. April 1826 | 1826040132 |
| Louis Spohr an Wilhelm Speyer in Offenbach | Kassel, Donnerstag 6. April 1826 | 1826040602 |
| Wilhelm Speyer an Louis Spohr in Kassel | Offenbach, Sonnabend 1. April 1826 | 1826040132 |
| Louis Spohr an Wilhelm Speyer in Offenbach | Kassel, Donnerstag 6. April 1826 | 1826040602 |