BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 18.01.1907
BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 15.02.1907
BRIEF OHNE UMSCHLAG Focke, Wilhelm Olbers Author: Focke, Wilhelm Olbers Recipient: Haeckel, Ernst Dating: 15.05.1907
BRIEF OHNE UMSCHLAG Albers, Hellmuth Author: Albers, Hellmuth Recipient: Haeckel, Ernst Dating: 17.02.1907
BRIEF [O.A.] Lüdeking, H. Author: Lüdeking, H. Recipient: Haeckel, Ernst Corporation: Bremischer Lehrer-Verein Dating: 25.11.1907