BRIEF [O.A.] Semon, Richard W... Author: Semon, Richard W... Recipient: Haeckel, Elisabeth Dating: 22.04.1915
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Elisabeth Dating: 16.01.1915
BRIEF [O.A.] Hintze, Wilhelmine Author: Hintze, Wilhelmine Recipient: Haeckel, Elisabeth Dating: 02.05.1915
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Elisabeth Dating: 27.10.1915