BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Unbekannt (Mutter?) Dating: 14.04.1878
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Familie Haeckel in Jena und Potsdam Dating: 20.04.1878
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Familie Haeckel in Potsdam Dating: 21.04.1878
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Familie Haeckel in Potsdam Dating: 26.04.1878
BRIEF [O.A.] Eurinac, Adolf E... Author: Eurinac, Adolf E... Recipient: Haeckel, Ernst Dating: 18.09.1887