BILDPOSTKARTE Kindlimann, Conrad Author: Kindlimann, Conrad Recipient: Haeckel, Ernst Dating: 15.02.1909
BILDPOSTKARTE Bretschneider, Fr.; Ennert, Wilhelm [et al.] Author: Bretschneider, Fr.; Ennert, Wilhelm [et al.] Recipient: Haeckel, Ernst Dating: 10.02.1909
BILDPOSTKARTE Hinderdael, Irmgard van Author: Hinderdael, Irmgard van Recipient: Haeckel, Ernst Dating: 16.02.1914
BILDPOSTKARTE Haeckel, Walter Author: Haeckel, Walter Recipient: Mentz, Georg; Mentz, Frida Dating: 16.06.1912