BRIEF [O.A.] Kreuzpointner, Josef Author: Kreuzpointner, Josef Recipient: Haeckel, Ernst Dating: 17.06.1911
BRIEF [O.A.] Kreuzpointner, Josef Author: Kreuzpointner, Josef Recipient: Haeckel, Ernst Dating: 22.06.1911
BRIEF OHNE UMSCHLAG Hertwig, Richard Author: Hertwig, Richard Recipient: Haeckel, Ernst Dating: 17.05.1911
PORTRÄTPOSTKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst Dating: 05.12.1911
PORTRÄTPOSTKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Agnes Dating: 12.03.1911