BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 16.11.1915
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 20.12.1915
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 08.02.1914
PORTRAITPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 16.02.1914