BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rautenfeld, Paul von Dating: 17.07.1901
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Besser, Käthe Dating: 21.06.1901
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Besser, Käthe Dating: 19.05.1901
BRIEF OHNE UMSCHLAG Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 24.11.1901
BRIEF [O.A.] Gray, Alexander Author: Gray, Alexander Recipient: Haeckel, Ernst Corporation: Millport Marine Biological Station Dating: 19.04.1901
BILDPOSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 22.12.1901
BRIEF OHNE UMSCHLAG Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 29.12.1901