BRIEF [O.A.] Ploeger, Wilhelmine Author: Ploeger, Wilhelmine Recipient: Haeckel, Ernst Dating: 03.05.1910
BRIEF [O.A.] Yates, Lorenzo G... Author: Yates, Lorenzo G... Recipient: Haeckel, Ernst Dating: 25.04.1889
BRIEF [O.A.] Yates, Lorenzo G... Author: Yates, Lorenzo G... Recipient: Haeckel, Ernst Dating: 04.07.1889
BRIEF [O.A.] Séckel, N... D... Author: Séckel, N... D... Recipient: Haeckel, Ernst Dating: 13.01.1911
BRIEF [O.A.] Blutharsche, Karl F... Author: Blutharsche, Karl F... Recipient: Haeckel, Ernst Dating: 24.04.1912
BRIEF [O.A.] Sevey, Ellen J... Author: Sevey, Ellen J... Recipient: Haeckel, Ernst Dating: 06.06.1909
