BRIEF OHNE UMSCHLAG Kraefft, Gustav Author: Kraefft, Gustav Recipient: Haeckel, Ernst Dating: 24.11.1894
BRIEF OHNE UMSCHLAG Kraefft, Gustav Author: Kraefft, Gustav Recipient: Haeckel, Ernst Dating: 31.10.1892
BRIEF OHNE UMSCHLAG Kraefft, Gustav Author: Kraefft, Gustav Recipient: Haeckel, Ernst Dating: 25.11.1896