BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rottenburg, Paul von Dating: 31.10.1897
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rottenburg, Paul von Dating: 20.12.1897
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rottenburg, Paul von Dating: 25.12.1897