BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Breitenbach, Wilhelm Dating: 26.12.1913
BRIEF OHNE UMSCHLAG Flegel, Heinrich Author: Flegel, Heinrich Recipient: Haeckel, Ernst Dating: 16.02.??
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sethe, Bertha Dating: ca. 24.01.1886
KARTE Preyer, William Thierry Author: Preyer, William Thierry Recipient: Haeckel, Ernst Dating: 22.07.XX