Dupont, Johannes Franz : Bianca Siffredi
| Louis Spohr an Johannes Franz Dupont in Hamburg | Kassel, Freitag 3. April 1857 | 1857040314 |
| Johannes Franz Dupont an Louis Spohr in Kassel | Hamburg, Donnerstag 1. Oktober 1857 | 1857100144 |
| Louis Spohr an Johannes Franz Dupont in Hamburg | Kassel, Freitag 3. April 1857 | 1857040314 |
| Johannes Franz Dupont an Louis Spohr in Kassel | Hamburg, Donnerstag 1. Oktober 1857 | 1857100144 |