BRIEF [O.A.] ...lemann, Theodor Author: ...lemann, Theodor Recipient: Haeckel, Ernst Dating: 10.04.1905
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: de Gruyter, Walter Dating: 25.04.1905
BRIEF [O.A.] Haeckel, Siegfried Author: Haeckel, Siegfried Recipient: Haeckel, Ernst Dating: 24.12.1905
