BRIEF OHNE UMSCHLAG Treub, Melchior Author: Treub, Melchior Recipient: Haeckel, Ernst Dating: 23.05.1900
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rooseboom Pit, Nanny Dating: 28.12.1900
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rooseboom Pit, Nanny Dating: 24.12.1900
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rodenberg, Julius Dating: 10.11.1900