POSTKARTE Rautenfeld, Paul von Author: Rautenfeld, Paul von Recipient: Haeckel, Ernst Dating: 16.09.1915
BRIEF [O.A.] Verbeek, R... W... M... Author: Verbeek, R... W... M... Recipient: Haeckel, Ernst Dating: 19.10.1900
BRIEF [O.A.] Verbeek, R... W... M... Author: Verbeek, R... W... M... Recipient: Haeckel, Ernst Dating: 09.12.1900
BRIEF [O.A.] Verbeek, R... W... M... Author: Verbeek, R... W... M... Recipient: Haeckel, Ernst Dating: 30.01.1901
BRIEF [O.A.] Verbeek, R... W... M... Author: Verbeek, R... W... M... Recipient: Haeckel, Ernst Dating: 20.12.1900
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Agnes; Haeckel, Emma Dating: 25.12.1900
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Agnes Dating: 16.10.1900