BRIEF [O.A.] Walter-Biondetti, C... Author: Walter-Biondetti, C... Recipient: Haeckel, Ernst Dating: 22.06.1907
BRIEF [O.A.] Walter-Biondetti, C... Author: Walter-Biondetti, C... Recipient: Haeckel, Ernst Dating: 08.03.1908
POSTKARTE Walter-Biondetti, C... Author: Walter-Biondetti, C... Recipient: Haeckel, Ernst Dating: 02.??.????
POSTKARTE Walter-Biondetti, C... Author: Walter-Biondetti, C... Recipient: Haeckel, Ernst Dating: 14.02.1911