BRIEF [O.A.] Jaffe, Otto Erich Author: Jaffe, Otto Erich Recipient: Haeckel, Ernst Dating: 15.02.1911
POSTKARTE Zachariewicz, Julian von Author: Zachariewicz, Julian von Recipient: Haeckel, Ernst Dating: 04.02.1917
BRIEF [O.A.] Zachariewicz, Julian von Author: Zachariewicz, Julian von Recipient: Haeckel, Ernst Dating: 13.02.1919
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 13.04.1898
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 16.04.1898
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 24.04.1898
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 09.03.1899
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 03.04.1899
POSTKARTE Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 08.06.1899