BRIEF [O.A.] Deregi, Oskar Author: Deregi, Oskar Recipient: Haeckel, Ernst Corporation: Nemzeti Szinház Dating: 11.09.1904
BRIEF [O.A.] Feichtinger, Alexius Baron Author: Feichtinger, Alexius Baron Recipient: Haeckel, Ernst Dating: 09.02.1914
BRIEF [O.A.] Breuer, Cornel H. Author: Breuer, Cornel H. Recipient: Haeckel, Ernst Dating: 10.10.1904