BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 20.02.1913
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 24.02.1918
PORTRÄTPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 13.05.1915
BILDPOSTKARTE Ernst Haeckel Author: Ernst Haeckel Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 31.12.1910
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 27.04.1915
BRIEF MIT UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 21.02.1909
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 22.02.1914
POSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Sprenger, Gustav; Sprenger, Therese Dating: 31.12.1912