BRIEF [O.A.] Loening, Margarete Author: Loening, Margarete Recipient: Haeckel, Ernst Dating: 12.06.1894
BRIEF [O.A.] Loening, Margarete Author: Loening, Margarete Recipient: Haeckel, Ernst Dating: 25.09.1916
BRIEF [O.A.] Loening, Margarete Author: Loening, Margarete Recipient: Haeckel, Ernst Dating: 04.10.1916