BRIEF [O.A.] Hubrecht, Ambrosius A... W... Author: Hubrecht, Ambrosius A... W... Recipient: Haeckel, Ernst Dating: 12.11.1889
BRIEF [O.A.] Hubrecht, Ambrosius A... W... Author: Hubrecht, Ambrosius A... W... Recipient: Haeckel, Ernst Corporation: Nederlandsche Dierkundige Vereeniging (Netherland Zoological Society) Dating: 25.09.1894
BRIEF [O.A.] Hubrecht, Ambrosius A... W... Author: Hubrecht, Ambrosius A... W... Recipient: Haeckel, Ernst Dating: 05.11.1896
BRIEF [O.A.] Engelmann, Theodor Wilhelm Author: Engelmann, Theodor Wilhelm Recipient: Haeckel, Ernst Dating: 07.10.1890
BRIEF [O.A.] Vosmaer, G... C. J. Author: Vosmaer, G... C. J. Recipient: Haeckel, Ernst Dating: 19.12.1889