BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Steenstrup, Japetus Dating: 20.11.1877
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Schultze, Fritz Dating: 15.10.1877
BRIEF [O.A.] Griesbach, Hermann Author: Griesbach, Hermann Recipient: Haeckel, Ernst Dating: 13.03.1877
BRIEF OHNE UMSCHLAG Greeff, Richard Author: Greeff, Richard Recipient: Haeckel, Ernst Dating: 27.01.1877
BRIEF OHNE UMSCHLAG Deubler, Konrad Author: Deubler, Konrad Recipient: Haeckel, Ernst Dating: 01.11.1877