BRIEF OHNE UMSCHLAG Jaeger, Gustav Author: Jaeger, Gustav Recipient: Haeckel, Ernst Dating: 23.05.1872
BRIEF OHNE UMSCHLAG Jaeger, Gustav Author: Jaeger, Gustav Recipient: Haeckel, Ernst Dating: 28.02.1872
BRIEF [O.A.] Koch, Eduard Author: Koch, Eduard Recipient: Haeckel, Ernst Corporation: E. Schweizerbart`sche Verlagsbuchhandlung, Eduard Koch Dating: 08.12.1872