BRIEF OHNE UMSCHLAG Haeckel, Karl Author: Haeckel, Karl Recipient: Haeckel, Ernst Dating: vor Juli 1865
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Agnes Dating: 20.10.1881
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Agnes Dating: ??.??.1876