Mangold, Carl Amand : Gudrun
| Carl Amand Mangold an Louis Spohr in Kassel | Darmstadt, Montag 19. August 1850 | 1850081944 |
| Louis Spohr an Carl Amand Mangold in Darmstadt | Kassel, Freitag 13. September 1850 | 1850091314 |
| Carl Amand Mangold an Louis Spohr in Kassel | Darmstadt, Donnerstag 26. September 1850 | 1850092644 |
| Louis Spohr an Carl Amand Mangold in Darmstadt | Kassel, Sonnabend 26. Oktober 1850 | 1850102614 |