BRIEF OHNE UMSCHLAG Hilger, Julius Author: Hilger, Julius Recipient: Haeckel, Ernst Dating: 01.05.1918
BRIEF OHNE UMSCHLAG Hilger, Julius Author: Hilger, Julius Recipient: Haeckel, Ernst Dating: 14.07.1918
BRIEF OHNE UMSCHLAG Hilger, Julius Author: Hilger, Julius Recipient: Haeckel, Ernst Dating: 10.02.1918