POSTKARTE Ortmann, Arnold E... Author: Ortmann, Arnold E... Recipient: Haeckel, Ernst Dating: 07.11.1893
BRIEF [O.A.] Orzeszko, Nikodem Author: Orzeszko, Nikodem Recipient: Haeckel, Ernst Dating: 21.11.1893
TELEGRAMM Heldburg, Helene Freifrau von Author: Heldburg, Helene Freifrau von Recipient: Haeckel, Ernst Dating: 16.02.1893
BRIEF [O.A.] Cassiere, G... Author: Cassiere, G... Recipient: Haeckel, Ernst Corporation: Société d'Étude des Sciences Naturelles Dating: 16.10.1893
POSTKARTE Gadeau de Kerville, Henri Author: Gadeau de Kerville, Henri Recipient: Haeckel, Ernst Dating: 01.05.1893