BRIEF [O.A.] Goerwitz, Hermann Author: Goerwitz, Hermann Recipient: Haeckel, Ernst Dating: 01.06.1881
BRIEF [O.A.] Goerwitz, Hermann Author: Goerwitz, Hermann Recipient: Haeckel, Ernst Dating: 09.06.1881
BRIEF [O.A.] Freudenberg, Ph... Author: Freudenberg, Ph... Recipient: Haeckel, Ernst Dating: 23.09.1881
BRIEF OHNE UMSCHLAG Aveling, Edward Bibbins Author: Aveling, Edward Bibbins Recipient: Haeckel, Ernst Corporation: Practical Science Laboratory Dating: 01.11.1881
BRIEF [O.A.] Tyrrell Leith, E... Author: Tyrrell Leith, E... Recipient: Haeckel, Ernst Dating: ??.??.1881