BRIEF [O.A.] Basso, Fritzi von Author: Basso, Fritzi von Recipient: Haeckel, Ernst Dating: 13.02.1904
BRIEF [O.A.] Bienenstein, Karl Author: Bienenstein, Karl Recipient: Haeckel, Ernst Dating: 29.11.1904
BRIEF [O.A.] Bienenstein, Karl Author: Bienenstein, Karl Recipient: Haeckel, Ernst Dating: 15.12.1904