BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 26.10.1893
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 05.04.1893
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 28.12.1893
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 09.02.1893