BRIEF OHNE UMSCHLAG Sohnemann, D... Author: Sohnemann, D... Recipient: Haeckel, Ernst Dating: 15.05.1900
BRIEF OHNE UMSCHLAG Ehlers, Ernst Author: Ehlers, Ernst Recipient: Haeckel, Ernst Corporation: Zootom. Institut Dating: 12.12.1870
TELEGRAMM Mikulicic, Miroslav Author: Mikulicic, Miroslav Recipient: Haeckel, Ernst Dating: 16.02.1914