BRIEF [O.A.] Peters, Paul Rudolf Author: Peters, Paul Rudolf Recipient: Haeckel, Ernst Dating: 05.05.1886
BRIEF [O.A.] Peters, Paul Rudolf Author: Peters, Paul Rudolf Recipient: Haeckel, Ernst Dating: 20.12.1886
BRIEF [O.A.] Liliencron, R... v. Author: Liliencron, R... v. Recipient: Haeckel, Ernst Dating: 17.05.1886
POSTKARTE Liliencron, R... v. Author: Liliencron, R... v. Recipient: Haeckel, Ernst Dating: 22.05.1886
BRIEF OHNE UMSCHLAG Kürschner, Joseph Author: Kürschner, Joseph Recipient: Haeckel, Ernst Dating: 20.02.1886