BRIEF [O.A.] Tóth von Felseö-Szopor, Marie Author: Tóth von Felseö-Szopor, Marie Recipient: Haeckel, Ernst Dating: 14.02.1904
BRIEF [O.A.] Lendenfeld, Robert von Author: Lendenfeld, Robert von Recipient: Haeckel, Ernst Corporation: Universität Innsbruck Dating: 20.10.1889
BRIEF [O.A.] Pesendorfer, Victor Author: Pesendorfer, Victor Recipient: Haeckel, Ernst Dating: 21.10.1909
BRIEF [O.A.] Neupauer, Joseph Ritter von Author: Neupauer, Joseph Ritter von Recipient: Haeckel, Ernst Dating: 03.01.1902
BRIEF [O.A.] Neupauer, Joseph Ritter von Author: Neupauer, Joseph Ritter von Recipient: Haeckel, Ernst Dating: 07.06.1902
BRIEF [O.A.] Neupauer, Joseph Ritter von Author: Neupauer, Joseph Ritter von Recipient: Haeckel, Ernst Dating: 03.12.1903