BRIEF [O.A.] Mereditt, R... E... Author: Mereditt, R... E... Recipient: Haeckel, Ernst Dating: 27.04.1905
BRIEF [O.A.] Semon, Richard W... Author: Semon, Richard W... Recipient: Haeckel, Ernst Dating: 31.10.1891
BRIEF [O.A.] Semon, Richard W... Author: Semon, Richard W... Recipient: Haeckel, Ernst Dating: 02.06.1892
BRIEF [O.A.] Weight, Ed... Perceval Author: Weight, Ed... Perceval Recipient: Haeckel, Ernst Corporation: Trinity College Dublin Dating: 05.03.1873
BRIEF [O.A.] Weight, Ed... Perceval Author: Weight, Ed... Perceval Recipient: Haeckel, Ernst Corporation: Trinity College Dublin Dating: 27.01.1877
BRIEF [O.A.] Weight, Ed... Perceval Author: Weight, Ed... Perceval Recipient: Haeckel, Ernst Corporation: Trinity College Dublin Dating: 25.03.1879
BRIEF [O.A.] Grosart, A... B... Author: Grosart, A... B... Recipient: Haeckel, Ernst Dating: 29.09.1894
BRIEF [O.A.] Jaffe, Paula Otto Author: Jaffe, Paula Otto Recipient: Haeckel, Ernst Dating: ??.02.1914