BRIEF OHNE UMSCHLAG Berninghaus, Walter Author: Berninghaus, Walter Recipient: Haeckel, Ernst Dating: 12.11.1907
BRIEF [O.A.] Bauke Author: Bauke Recipient: Haeckel, Ernst Corporation: Dr. Bauke (Th. Zell) Dating: 01.10.1907
POSTKARTE Bölsche, Wilhelm Author: Bölsche, Wilhelm Recipient: Haeckel, Ernst Corporation: Monistenabend Berlin Dating: 27.02.1907
ANSICHTSKARTE Bermann, Cipri Adolf; Bermann, Clara Author: Bermann, Cipri Adolf; Bermann, Clara Recipient: Haeckel, Ernst Dating: 31.12.1907
TELEGRAMM Waldeyer-Hartz, Wilhelm von Author: Waldeyer-Hartz, Wilhelm von Recipient: Haeckel, Ernst Dating: 07.03.1907
BRIEF OHNE UMSCHLAG Engelmann, Theodor Wilhelm Author: Engelmann, Theodor Wilhelm Recipient: Haeckel, Ernst Dating: 26.01.1907
TELEGRAMM Engelmann, Theodor Wilhelm Author: Engelmann, Theodor Wilhelm Recipient: Haeckel, Ernst Dating: 16.02.1907