BRIEF OHNE UMSCHLAG Retzius, Gustaf Author: Retzius, Gustaf Recipient: Haeckel, Ernst Dating: 19.11.1895
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 OHNE UMSCHLAG Schück, Henrik Author: Schück, Henrik Recipient: Haeckel, Ernst Corporation: Upsala Universitets – Rektor Dating: 16.08.1907
POSTKARTE Gyldén, Therese Author: Gyldén, Therese Recipient: Haeckel, Ernst; Haeckel, Agnes Dating: 30.12.1904
BRIEF OHNE UMSCHLAG Angström, Knut; Arrhenius, Svante Author: Angström, Knut; Arrhenius, Svante Recipient: Haeckel, Ernst