TELEGRAMM Recipient: Haeckel, Ernst Corporation: Sternwarte der Plagwitzer Strasse, Leipzig Dating: 20.08.1892
TELEGRAMM Geyer, ?; Schlutius ? Author: Geyer, ?; Schlutius ? Recipient: Haeckel, Ernst Dating: 20.08.1892
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sethe, Bertha Dating: 08.08.1892