POSTKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst; Haeckel, Agnes [Eltern] Dating: 25.04.1898
POSTKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst; Haeckel, Agnes [Eltern] Dating: 22.06.1898
BRIEF [O.A.] Meyer, Elisabeth Author: Meyer, Elisabeth Recipient: Haeckel, Ernst; Haeckel, Agnes [Eltern] Dating: 17.10.1898