BRIEF [O.A.] Schuster, Adolf Niklaus Author: Schuster, Adolf Niklaus Recipient: Haeckel, Ernst Dating: 18.11.1906
BRIEF [O.A.] Schaufenbühl, Friedrich Author: Schaufenbühl, Friedrich Recipient: Haeckel, Ernst Dating: 20.12.1906
BRIEF OHNE UMSCHLAG Dorsch, Hannah Author: Dorsch, Hannah Recipient: Haeckel, Ernst Dating: 14.02.1906
BRIEF OHNE UMSCHLAG Dorsch, Hannah Author: Dorsch, Hannah Recipient: Haeckel, Ernst Dating: 08.03.1906