BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Oscar; Hertwig, Richard Dating: 23.05.1871
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Oscar; Hertwig, Richard Dating: 15.07.1869
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Oscar; Hertwig, Richard Dating: 22.12.1871
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Oscar; Hertwig, Richard Dating: 03.03.1891
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Oscar; Hertwig, Richard Dating: 15.05.1871
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Hertwig, Oscar; Hertwig, Richard Dating: 29.01.1876