POSTKARTE Heldburg, Helene Freifrau von Author: Heldburg, Helene Freifrau von Recipient: Haeckel, Ernst Dating: 03.05.1900
BRIEF [O.A.] Stephen, Dorothea Author: Stephen, Dorothea Recipient: Haeckel, Ernst Dating: 28.10.1911
BRIEF [O.A.] Stephen, Dorothea Author: Stephen, Dorothea Recipient: Haeckel, Ernst Dating: 14.02.1911
TELEGRAMM Stephen, Helena; Stephen, Dorothea Author: Stephen, Helena; Stephen, Dorothea Recipient: Haeckel, Ernst Dating: 19.05.1911
BRIEF [O.A.] Stephen, Dorothea Author: Stephen, Dorothea Recipient: Haeckel, Ernst Dating: 19.11.1910