BRIEF [O.A.] Kirchhoff, Adolf Arthur Author: Kirchhoff, Adolf Arthur Recipient: Haeckel, Ernst Corporation: Berliner Wissenschaftliche Correspondenz Dating: 21.08.1896
BRIEF [O.A.] Zabel, Rudolf Author: Zabel, Rudolf Recipient: Haeckel, Ernst Corporation: Akademische Rundschau, Redaction Dating: 07.02.1896
BRIEF [O.A.] Suphan, Bernhard Author: Suphan, Bernhard Recipient: Haeckel, Ernst Corporation: Goethe- und Schiller-Archiv Dating: ??.05.1896