POSTKARTE Wereschtschagin, Wassili Author: Wereschtschagin, Wassili Recipient: Haeckel, Ernst Dating: 27.03.1901
ANSICHTSKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 17.01.1902
ANSICHTSKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 28.01.1902
POSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 20.02.1906
POSTKARTE Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: ??.??.1906
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 21.10.1881
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 28.03.1882