BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 12.04.1886
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 16.09.1886
BRIEF OHNE UMSCHLAG Haeckel, Charlotte Author: Haeckel, Charlotte Recipient: Haeckel, Ernst Dating: 01.02.1886
BRIEF OHNE UMSCHLAG Haeckel, Charlotte Author: Haeckel, Charlotte Recipient: Haeckel, Ernst Dating: 10.05.1886