BRIEF [O.A.] Bloch, Iwan Author: Bloch, Iwan Recipient: Haeckel, Ernst Corporation: Zeitschrift für Sexualwissenschaft Dating: 18.09.1917
BRIEF [O.A.] Klostermann, Helene Author: Klostermann, Helene Recipient: Haeckel, Ernst Dating: 02.01.1897
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 07.12.1897
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 19.12.1897
BRIEF [O.A.] Jacobsthal, Joh... Eduard Author: Jacobsthal, Joh... Eduard Recipient: Haeckel, Ernst Dating: 16.01.1898
BRIEF [O.A.] Jaffe, Otto Erich Author: Jaffe, Otto Erich Recipient: Haeckel, Ernst Dating: 15.02.1911