BRIEF OHNE UMSCHLAG Bertheau, Georg Author: Bertheau, Georg Recipient: Haeckel, Ernst Dating: 10.02.1904
BRIEF [O.A.] Wagner, E... [Geheimrat] Author: Wagner, E... [Geheimrat] Recipient: Haeckel, Ernst Dating: 22.12.1904
BRIEF [O.A.] Helbing, Paul A... Author: Helbing, Paul A... Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF [O.A.] Nüßlin, Otto Author: Nüßlin, Otto Recipient: Haeckel, Ernst Corporation: Zool. Institut der TH Dating: 15.02.1904
BRIEF [O.A.] Kutzschenbach, Arthur von Author: Kutzschenbach, Arthur von Recipient: Haeckel, Ernst Dating: 07.01.1904