ANSICHTSKARTE Ammon, Sophie von Author: Ammon, Sophie von Recipient: Haeckel, Ernst Dating: 05.04.1910
BRIEF OHNE UMSCHLAG Gegenbaur, Carl Author: Gegenbaur, Carl Recipient: Haeckel, Ernst Dating: 13.04.1892
BRIEF OHNE UMSCHLAG Andreae, Conrad Author: Andreae, Conrad Recipient: Haeckel, Ernst Dating: 27.07.1914
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Strasburger, Eduard Dating: 09.12.1903
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 16.02.1904
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Engelmann, Wilhelm Dating: 16.02.1904
BILDPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Verworn, Max; Verworn, Josephine Dating: 29.12.1903