BRIEF [O.A.] Lambrecht, Koloman Author: Lambrecht, Koloman Recipient: Haeckel, Ernst Dating: 07.04.1914
BRIEF [O.A.] Margittai, Richard Author: Margittai, Richard Recipient: Haeckel, Ernst Dating: 15.03.1914
BRIEF [O.A.] Feichtinger, Alexius Baron Author: Feichtinger, Alexius Baron Recipient: Haeckel, Ernst Dating: 09.02.1914