BRIEF OHNE UMSCHLAG Grober, Julius Author: Grober, Julius Recipient: Haeckel, Ernst Dating: 03.04.1909
BRIEF OHNE UMSCHLAG Grober, Julius Author: Grober, Julius Recipient: Haeckel, Ernst Dating: 26.07.1909
BRIEF OHNE UMSCHLAG Anonym (P. B.) Author: Anonym (P. B.) Recipient: Haeckel, Ernst Dating: ??.06.1907
BRIEF OHNE UMSCHLAG Krupp, Margarete Author: Krupp, Margarete Recipient: Haeckel, Ernst Dating: 28.12.1902
BRIEF OHNE UMSCHLAG Krupp, Margarete Author: Krupp, Margarete Recipient: Haeckel, Ernst Dating: 15.03.1903
BRIEF OHNE UMSCHLAG Krupp, Friedrich Alfred Author: Krupp, Friedrich Alfred Recipient: Haeckel, Ernst Dating: 06.09.1898