BRIEF OHNE UMSCHLAG Weismann, August Author: Weismann, August Recipient: Haeckel, Ernst Dating: 08.02.1914
ANSICHTSKARTE Lother, Friedrich Author: Lother, Friedrich Recipient: Haeckel, Ernst Dating: 14.02.1914
TELEGRAMM Wiedersheim, Robert Author: Wiedersheim, Robert Recipient: Haeckel, Ernst Dating: 16.02.1914