POSTKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst Dating: 1904.??.?? - 1905.??.??
ANSICHTSKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst; Haeckel, Agnes [Eltern] Dating: 31.05.1914
BRIEF [O.A.] Haeckel, Walther Author: Haeckel, Walther Recipient: Allmers, Hermann Dating: 14.05.1885
PORTRÄTPOSTKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst Dating: 12.02.1901
BRIEF OHNE UMSCHLAG Haeckel, Walther Author: Haeckel, Walther Recipient: Hauptmann, Gerhart Dating: 13.11.1937
BRIEF OHNE UMSCHLAG Haeckel, Walther Author: Haeckel, Walther Recipient: Schmidt, Heinrich Dating: 21.02.1928