BRIEF OHNE UMSCHLAG Greeff, Richard Author: Greeff, Richard Recipient: Haeckel, Ernst Dating: 22.11.1889
BRIEF OHNE UMSCHLAG Gandtner, Otto Author: Gandtner, Otto Recipient: Haeckel, Ernst Dating: 26.02.1889
BRIEF OHNE UMSCHLAG Gandtner, Otto Author: Gandtner, Otto Recipient: Haeckel, Ernst Dating: 10.12.1889
BRIEF [O.A.] Göring, Hugo Author: Göring, Hugo Recipient: Haeckel, Ernst Corporation: Die Neue Deutsche Schule Dating: 27.05.1889
BRIEF [O.A.] Göring, Hugo Author: Göring, Hugo Recipient: Haeckel, Ernst Corporation: Die Neue Deutsche Schule Dating: 29.05.1889