BRIEF [O.A.] Trautmann, Heinrich Author: Trautmann, Heinrich Recipient: Haeckel, Ernst Dating: 07.08.1903
BRIEF [O.A.] Hasse, Johann Carl Author: Hasse, Johann Carl Recipient: Haeckel, Ernst Dating: 20.12.1873
BRIEF [O.A.] Hasse, Johann Carl Author: Hasse, Johann Carl Recipient: Haeckel, Ernst Dating: 15.01.1894
BRIEF [O.A.] Hasse, Johann Carl Author: Hasse, Johann Carl Recipient: Haeckel, Ernst Dating: 19.03.1894
BRIEF [O.A.] Hasse, Johann Carl Author: Hasse, Johann Carl Recipient: Haeckel, Ernst Dating: 21.06.1894
BRIEF [O.A.] Hasse, Johann Carl Author: Hasse, Johann Carl Recipient: Haeckel, Ernst Dating: 12.08.1894
BRIEF [O.A.] Hasse, Johann Carl Author: Hasse, Johann Carl Recipient: Haeckel, Ernst Dating: 19.10.1874
BRIEF [O.A.] Habellock, Herbert Author: Habellock, Herbert Recipient: Haeckel, Ernst Dating: 15.02.1913