BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 01.01.1917
BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 14.02.1917
BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 05.03.1917
POSTKARTE Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 11.04.1917
BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 28.04.1917