OFFENER BRIEF Eichhorn, Gustav Author: Eichhorn, Gustav Recipient: Schaffner, Jakob Dating: 18.10.1914
OFFENER BRIEF Forel, Auguste Author: Forel, Auguste Recipient: Haeckel, Ernst Dating: 1914.12.01 [davor]
OFFENER BRIEF Kallmorgen, Friedrich Author: Kallmorgen, Friedrich Recipient: Haeckel, Ernst Dating: 17.10.1914
OFFENER BRIEF Allburtt, Clifford; Allen, T. W. [et al.] Author: Allburtt, Clifford; Allen, T. W. [et al.] Recipient: Diverse (Die Deutschen Akademischen Kreise) Corporation: Professoren Großbritanniens Dating: 1914.12.24 [eigh. Haeckel]