POSTKARTE Finsterbusch, Ludwig Author: Finsterbusch, Ludwig Recipient: Haeckel, Ernst Dating: 25.03.1892
BRIEF OHNE UMSCHLAG Finsterbusch, Ludwig Author: Finsterbusch, Ludwig Recipient: Haeckel, Ernst Dating: 19.07.1892
POSTKARTE Finsterbusch, Ludwig Author: Finsterbusch, Ludwig Recipient: Haeckel, Ernst Dating: 30.12.1892