BRIEF [O.A.] Steman, Friedrich Author: Steman, Friedrich Recipient: Haeckel, Ernst Dating: 26.02.1913
BRIEF [O.A.] Steman, Friedrich Author: Steman, Friedrich Recipient: Haeckel, Ernst Dating: 13.04.1913
BRIEF MIT UMSCHLAG Steman, Friedrich Author: Steman, Friedrich Recipient: Haeckel, Ernst Dating: 28.09.1913
BRIEF [O.A.] Steman, Friedrich Author: Steman, Friedrich Recipient: Haeckel, Ernst Corporation: Vorwärts - Berliner Volksblatt Dating: 27.09.1913
BRIEF [O.A.] Steman, Friedrich Author: Steman, Friedrich Recipient: Haeckel, Ernst Dating: 12.11.1913