BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 11.08.1881
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 08.01.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 12.01.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 15.05.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 15.06.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 30.06.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 03.09.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 26.09.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 06.10.1882
BRIEF [O.A.] Keller-Leuzinger, Franz Author: Keller-Leuzinger, Franz Recipient: Haeckel, Ernst Dating: 09.10.1882