BRIEF OHNE UMSCHLAG Kükenthal, Willy Author: Kükenthal, Willy Recipient: Haeckel, Ernst Dating: 08.08.1894
BRIEF [O.A.] Küstermann, Franz Author: Küstermann, Franz Recipient: Haeckel, Ernst Dating: 18.10.1869
BRIEF [O.A.] Loeb, Arthur Author: Loeb, Arthur Recipient: Hanitsch, Richard Corporation: Katz Brothers Dating: 02.10.1900
TELEGRAMM Rautenfeld, Paul von Author: Rautenfeld, Paul von Recipient: Haeckel, Ernst Dating: 16.02.1904