BRIEF OHNE UMSCHLAG Kürschner, Joseph Author: Kürschner, Joseph Recipient: Haeckel, Ernst Dating: 20.02.1886
BRIEF OHNE UMSCHLAG Kürschner, Joseph Author: Kürschner, Joseph Recipient: Haeckel, Ernst Dating: 28.02.1886
BRIEF [O.A.] Kürschner, Joseph Author: Kürschner, Joseph Recipient: Haeckel, Ernst Dating: 28.04.1886