Nehmann, Euchar Author: Nehmann, Euchar Recipient: Haeckel, Ernst Corporation: Kosmos - Gesellschaft der Naturfreunde Dating: 08.02.1907
BRIEF [O.A.] Kröner, Alfred Author: Kröner, Alfred Recipient: Haeckel, Ernst Corporation: Alfred Kröner Verlag Dating: 03.05.1907
BRIEF [O.A.] Kröner, Alfred Author: Kröner, Alfred Recipient: Haeckel, Ernst Corporation: Alfred Kröner Verlag Dating: 04.03.1907
BRIEF [O.A.] Lehmann, Fritz Author: Lehmann, Fritz Recipient: Haeckel, Ernst Corporation: Fritz Lehmann Verlag Dating: 04.09.1907
BRIEF [O.A.] Lehmann, Fritz Author: Lehmann, Fritz Recipient: Haeckel, Ernst Corporation: Fritz Lehmann Verlag Dating: 07.12.1907