BRIEF OHNE UMSCHLAG Günther, Franz Author: Günther, Franz Recipient: Haeckel, Ernst Dating: 08.12.1886
BRIEF OHNE UMSCHLAG Günther, Franz Author: Günther, Franz Recipient: Haeckel, Ernst Dating: 24.12.1886
BRIEF [O.A.] Davidoff, Alexander Author: Davidoff, Alexander Recipient: Haeckel, Ernst Dating: 01.11.1897
BRIEF [O.A.] Davidoff, Alexander Author: Davidoff, Alexander Recipient: Haeckel, Ernst Dating: 08.12.1897
BRIEF [O.A.] Danzas, Nicolas de Author: Danzas, Nicolas de Recipient: Haeckel, Ernst Dating: 21.10.1888
BRIEF [O.A.] Froelich, Heinrich Author: Froelich, Heinrich Recipient: Haeckel, Ernst Dating: 23.02.1913
BRIEF [O.A.] Froelich, Heinrich Author: Froelich, Heinrich Recipient: Haeckel, Ernst Dating: 27.05.1914