BRIEF [O.A.] Fleischer, Richard Author: Fleischer, Richard Recipient: Haeckel, Ernst Dating: 04.11.1870
BRIEF [O.A.] Fleischer, Richard Author: Fleischer, Richard Recipient: Haeckel, Ernst Dating: 07.07.1870
BRIEF [O.A.] Grube, Adolf Eduard Author: Grube, Adolf Eduard Recipient: Haeckel, Ernst Dating: 18.05.1870
BRIEF [O.A.] Ritter, D... J... G... Author: Ritter, D... J... G... Recipient: Haeckel, Ernst Dating: 15.12.1870
BRIEF [O.A.] Ratzel, Friedrich Author: Ratzel, Friedrich Recipient: Haeckel, Ernst Dating: 08.02.1870
BRIEF [O.A.] Ratzel, Friedrich Author: Ratzel, Friedrich Recipient: Haeckel, Ernst Dating: 25.06.1870
BRIEF [O.A.] Hermann (Itrigsohn) Author: Hermann (Itrigsohn) Recipient: Haeckel, Ernst Dating: ??.10.1870