BRIEF OHNE UMSCHLAG Arrhenius, Svante Author: Arrhenius, Svante Recipient: Haeckel, Walter; Haeckel, Elisabeth Dating: 11.08.1919
BRIEF OHNE UMSCHLAG Arrhenius, Svante Author: Arrhenius, Svante Recipient: Haeckel, Walter Dating: 23.05.1920
POSTKARTE Bergstedt, J. A. Author: Bergstedt, J. A. Recipient: Haeckel, Ernst Corporation: Académie Royale Suédoise des Sciences Dating: 18.05.1909
BRIEF OHNE UMSCHLAG Ahlsell, Fritiof Author: Ahlsell, Fritiof Recipient: Haeckel, Ernst Dating: 23.02.1907
POSTKARTE Bergstedt, J... A... Author: Bergstedt, J... A... Recipient: Haeckel, Ernst Corporation: Académie Royale Suédoise des Sciences Dating: 01.07.1905
BRIEF [O.A.] Jägerskiold, L... A... Author: Jägerskiold, L... A... Recipient: Haeckel, Ernst Dating: 05.05.1902
BRIEF [O.A.] Jägerskiold, L... A... Author: Jägerskiold, L... A... Recipient: Haeckel, Ernst Dating: 01.08.1902