BRIEF OHNE UMSCHLAG Benedikt, Moritz Author: Benedikt, Moritz Recipient: Haeckel, Ernst Dating: 28.01.1918
BRIEF OHNE UMSCHLAG Benedikt, Moritz Author: Benedikt, Moritz Recipient: Haeckel, Ernst Dating: 31.01.1918
BRIEF [O.A.] Bettelheim, Anton Author: Bettelheim, Anton Recipient: Haeckel, Ernst Dating: 19.10.1890
BRIEF [O.A.] Bettelheim, Anton Author: Bettelheim, Anton Recipient: Haeckel, Ernst Dating: 14.01.1898