POSTKARTE Wereschtschagin, Wassili Author: Wereschtschagin, Wassili Recipient: Haeckel, Ernst Dating: 27.03.1901
BRIEF [O.A.] Schild, Johann Author: Schild, Johann Recipient: Haeckel, Ernst Corporation: Deutsch-Australische-Dampfschiffs-Gesellschaft Dating: 13.03.1901
BRIEF [O.A.] Nippold, Friedrich Author: Nippold, Friedrich Recipient: Haeckel, Ernst Dating: ??.06.1901
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Schultze, Bernhard Sigmund Dating: 28.08.1901
ANSICHTSKARTE Haeckel, Walther Author: Haeckel, Walther Recipient: Haeckel, Ernst; Haeckel, Agnes Dating: 19.07.1901
BRIEF [O.A.] Ratzel, Friedrich Author: Ratzel, Friedrich Recipient: Haeckel, Ernst Dating: 30.11.1901
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Georg II., Herzog von Sachsen-Meiningen Dating: 28.02.1901