BRIEF [O.A.] Semon, Maria; Semon, Richard Author: Semon, Maria; Semon, Richard Recipient: Haeckel, Ernst Dating: 02.02.1911
BRIEF [O.A.] Semon, Richard Wolfgang Author: Semon, Richard Wolfgang Recipient: Haeckel, Ernst Dating: 12.05.1911
BRIEF [O.A.] Semon, Richard Wolfgang Author: Semon, Richard Wolfgang Recipient: Haeckel, Ernst Dating: 04.07.1911
BRIEF [O.A.] Semon, Richard Wolfgang Author: Semon, Richard Wolfgang Recipient: Haeckel, Ernst Dating: 30.12.1911
BRIEF OHNE UMSCHLAG Aigner, Eduard Author: Aigner, Eduard Recipient: Haeckel, Ernst Corporation: Deutscher Monistenbund Dating: 17.03.1911
BRIEF OHNE UMSCHLAG Aigner, Eduard Author: Aigner, Eduard Recipient: Haeckel, Ernst Dating: 26.10.1911