ANSICHTSKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 22.02.1916
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 27.10.1857
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 28.04.1866
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 20.02.1868
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 20.12.1874
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 21.01.1907
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Focke, Wilhelm Olbers Dating: 01.01.1910