BRIEF OHNE UMSCHLAG Schleicher, August Author: Schleicher, August Recipient: Haeckel, Ernst Dating: 05.09.1863
BILLET Schleicher, August Author: Schleicher, August Recipient: Haeckel, Ernst; Haeckel, Anna Dating: 29.10.1863
BRIEF OHNE UMSCHLAG Zenker, Wilhelm Author: Zenker, Wilhelm Recipient: Haeckel, Ernst Dating: 28.04.1863
BRIEF [O.A.] Wagenschieber, W... Author: Wagenschieber, W... Recipient: Haeckel, Ernst Dating: 12.09.1863