POSTKARTE Wereschtschagin, Wassili Author: Wereschtschagin, Wassili Recipient: Haeckel, Ernst Dating: 27.03.1901
BILDPOSTKARTE Ammon, Sophie von Author: Ammon, Sophie von Recipient: Haeckel, Agnes Dating: 1908.??.?? [?]
BRIEF [O.A.] Barry Author: Barry Recipient: Haeckel, Ernst Corporation: Cabinet du Khedive Dating: 21.03.1876