BRIEF OHNE UMSCHLAG Umrath, Wilhelm Author: Umrath, Wilhelm Recipient: Haeckel, Ernst Dating: 19.02.1915
BRIEF OHNE UMSCHLAG Recipient: Haeckel, Ernst Corporation: Wiener Bank-Verein. Filiale Prag. Dating: 19.02.1915
BRIEF [O.A.] Schmerler, Samuel Author: Schmerler, Samuel Recipient: Haeckel, Ernst Dating: 16.02.1915