BRIEF [O.A.] Vielhaber, Walther Author: Vielhaber, Walther Recipient: Haeckel, Ernst Corporation: Deutscher Monistenbund Ortsgruppe Groß-Berlin Dating: 24.10.1910
BRIEF [O.A.] Vollrath, Karl Author: Vollrath, Karl Recipient: Haeckel, Ernst Corporation: Redaction der Volks-Zeitung Dating: 25.11.1910
BRIEF [O.A.] Vollrath, Karl Author: Vollrath, Karl Recipient: Haeckel, Ernst Corporation: Redaction der Volks-Zeitung Dating: 11.07.1910
TELEGRAMM Kleinsorgen, Wilhelm Author: Kleinsorgen, Wilhelm Recipient: Haeckel, Ernst Dating: 16.02.1910
POSTKARTE Jacobsohn, Siegfried Author: Jacobsohn, Siegfried Recipient: Haeckel, Ernst Dating: 15.02.1910
BRIEF [O.A.] Recipient: Haeckel, Ernst Corporation: Ullstein & Co. Verlagsbuchhandlung Dating: 11.06.1910
BRIEF [O.A.] Recipient: Haeckel, Ernst Corporation: Ullstein & Co. Verlagsbuchhandlung Dating: 09.11.1910