BRIEF OHNE UMSCHLAG Erdmann, Gustav Adolf Author: Erdmann, Gustav Adolf Recipient: Haeckel, Ernst Dating: 15.02.1894
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 OHNE UMSCHLAG Carter, Franklin B. Author: Carter, Franklin B. Recipient: Haeckel, Ernst Dating: 20.04.1894
BRIEF [O.A.] Camerano, Lorenzo Author: Camerano, Lorenzo Recipient: Haeckel, Ernst Corporation: Museo Zoologico di Torino Dating: 30.06.1894
BRIEF [O.A.] Caporali, Enrico Author: Caporali, Enrico Recipient: Haeckel, Ernst Corporation: La Nuova Scienza Rivista dell'Istruzione Superiore Dating: 02.10.1894
BRIEF OHNE UMSCHLAG Engelmann, Theodor Wilhelm Author: Engelmann, Theodor Wilhelm Recipient: Haeckel, Ernst Dating: 15.02.1894