BRIEF OHNE UMSCHLAG Strasburger, Eduard Author: Strasburger, Eduard Recipient: Haeckel, Ernst Dating: 01.10.1872
BRIEF [O.A.] Schneider, G... H... Author: Schneider, G... H... Recipient: Haeckel, Ernst Dating: 08.06.1872
BRIEF [O.A.] Schneider, G... H... Author: Schneider, G... H... Recipient: Haeckel, Ernst Dating: 29.08.1872