BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 04.08.1918
POSTKARTE Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 03.01.1918
BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 14.02.1918
BRIEF [O.A.] Finsterlin, Hermann Author: Finsterlin, Hermann Recipient: Haeckel, Ernst Dating: 13.02.1918
BRIEF [O.A.] Finsterlin, Hermann Author: Finsterlin, Hermann Recipient: Haeckel, Ernst Dating: 28.03.1918
BRIEF [O.A.] Eylmer, Heinrich Author: Eylmer, Heinrich Recipient: Haeckel, Ernst Corporation: Universitäts-Frauenklinik Dating: 15.02.1918
