BRIEF OHNE UMSCHLAG Dodel-Port, Arnold Author: Dodel-Port, Arnold Recipient: Haeckel, Ernst Dating: 14.02.1907
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Haeckel, Walter; Haeckel, Agnes Dating: 09.10.1889
BRIEF OHNE UMSCHLAG Dodel-Port, Arnold Author: Dodel-Port, Arnold Recipient: Haeckel, Ernst Dating: 24.02.1904
BRIEF OHNE UMSCHLAG Dodel-Port, Arnold Author: Dodel-Port, Arnold Recipient: Haeckel, Ernst Dating: 20.06.1906
BRIEF OHNE UMSCHLAG Gegenbaur, Carl Author: Gegenbaur, Carl Recipient: Haeckel, Ernst Dating: 10.04.1889