| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Montag 3. Januar 1842 | 1842010348 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Dienstag 8. März 1842 | 1842030848 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Dienstag 25. Oktober 1842 | 1842102548 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Donnerstag 15. Dezember 1842 | 1842121548 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Dienstag 4. April 1843 | 1843040448 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Donnerstag 25. Mai 1843 | 1843052548 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Sonntag 24. September 1843 | 1843092448 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Sonntag 19. November 1843 | 1843111948 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Sonntag 10. August 1845 | 1845081048 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Freitag 3. April 1846 | 1846040348 |
| Carl Georg Firnhaber an Louis Spohr in Kassel | Hanau, Mittwoch 3. April 1850 | 1850040348 |
