POSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 12.06.1893
BRIEF [O.A.] Kürschner, Joseph Author: Kürschner, Joseph Recipient: Haeckel, Ernst Corporation: Zeitung "Aus Fremden Zungen" Dating: 23.06.1893
BRIEF [O.A.] Kürschner, Joseph Author: Kürschner, Joseph Recipient: Haeckel, Ernst Corporation: Zeitung "Aus Fremden Zungen" Dating: 12.07.1893