BRIEF [O.A.] Schillemant, H... W... G... Author: Schillemant, H... W... G... Recipient: Haeckel, Ernst Dating: 25.08.1904
TELEGRAMM Hahn, Hugo Author: Hahn, Hugo Recipient: Haeckel, Ernst Corporation: Zoologischer Garten Jena Dating: 16.02.1904
BRIEF [O.A.] Linck, Gottlob Eduard Author: Linck, Gottlob Eduard Recipient: Haeckel, Ernst Dating: 14.02.1904
BRIEF [O.A.] Lipsius, Friedrich Author: Lipsius, Friedrich Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF OHNE UMSCHLAG Maurer, Friedrich Author: Maurer, Friedrich Recipient: Haeckel, Ernst Dating: 14.02.1904