POSTKARTE Benecke, Ernst Wilhelm Author: Benecke, Ernst Wilhelm Recipient: Haeckel, Ernst Dating: 29.12.1895
BRIEF [O.A.] Döderlein, Ludwig Author: Döderlein, Ludwig Recipient: Haeckel, Ernst Dating: 04.12.1887
BRIEF [O.A.] Döderlein, Ludwig Author: Döderlein, Ludwig Recipient: Haeckel, Ernst Dating: 04.10.1895