BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Siebold, Carl Theodor Ernst von Dating: 18.02.1879
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Richard Dating: 04.04.1879
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Retzius, Gustaf Dating: 21.12.1879
TELEGRAMM Haeckel, Ernst [?] Author: Haeckel, Ernst [?] Recipient: Rottenburg, Paul von Dating: 09.08.1879
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Niess, Albert Dating: 31.05.1879