BRIEF OHNE UMSCHLAG Hertwig, Oscar Author: Hertwig, Oscar Recipient: Haeckel, Ernst Dating: 16.12.1897
BRIEF OHNE UMSCHLAG Hertwig, Oscar Author: Hertwig, Oscar Recipient: Haeckel, Ernst Dating: 03.03.1899
BRIEF OHNE UMSCHLAG Hertwig, Oscar Author: Hertwig, Oscar Recipient: Haeckel, Ernst Dating: 23.05.1899
BRIEF OHNE UMSCHLAG Hertwig, Oscar Author: Hertwig, Oscar Recipient: Haeckel, Ernst Dating: 13.06.1899