BRIEF [O.A.] Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 28.07.1881
BRIEF [O.A.] Tyrrell Leith, E... Author: Tyrrell Leith, E... Recipient: Haeckel, Ernst Dating: ??.??.1881
BRIEF [O.A.] Marshall-Ward, H... Author: Marshall-Ward, H... Recipient: Haeckel, Ernst Dating: 30.12.1881
BRIEF OHNE UMSCHLAG Freudenberg, Philipp Author: Freudenberg, Philipp Recipient: Haeckel, Ernst Dating: 18.07.1881
BRIEF OHNE UMSCHLAG Freudenberg, Philipp Author: Freudenberg, Philipp Recipient: Haeckel, Ernst Dating: 29.09.1881
BRIEF [O.A.] Tyrrell Leith, E... Author: Tyrrell Leith, E... Recipient: Haeckel, Ernst Dating: 15.11.1881