BRIEF OHNE UMSCHLAG Pringsheim, Nathanael Author: Pringsheim, Nathanael Recipient: Haeckel, Ernst Dating: 08.01.1881
BRIEF OHNE UMSCHLAG Pringsheim, Nathanael Author: Pringsheim, Nathanael Recipient: Haeckel, Ernst Dating: 13.01.1881
KARTE Pringsheim, Nathanael Author: Pringsheim, Nathanael Recipient: Haeckel, Ernst Dating: 16.11.1881