BRIEF [O.A.] Juliusburger, Otto Author: Juliusburger, Otto Recipient: Haeckel, Ernst Dating: 16.02.1919
BRIEF [O.A.] Juliusburger, Otto Author: Juliusburger, Otto Recipient: Haeckel, Ernst Dating: 06.04.1919
BRIEF [O.A.] Juliusburger, Otto Author: Juliusburger, Otto Recipient: Haeckel, Ernst Dating: 02.06.1919