BRIEF [O.A.] Ziegler, Heinrich Ernst Author: Ziegler, Heinrich Ernst Recipient: Haeckel, Ernst Dating: 24.11.1900
BRIEF [O.A.] Theszóll, Charles Author: Theszóll, Charles Recipient: Haeckel, Ernst Dating: 23-02-1900
BRIEF OHNE UMSCHLAG Grazie, Marie Eugenie delle Author: Grazie, Marie Eugenie delle Recipient: Haeckel, Ernst Dating: 25.05.1900
ANSICHTSKARTE Grazie, Marie Eugenie delle; Müllner, Laurenz Author: Grazie, Marie Eugenie delle; Müllner, Laurenz Recipient: Haeckel, Ernst Dating: 20.07.1900
ANSICHTSKARTE Grazie, Marie Eugenie delle; Müllner, Laurenz Author: Grazie, Marie Eugenie delle; Müllner, Laurenz Recipient: Haeckel, Ernst Dating: 08.08.1900
BRIEF [O.A.] Reinicke, Emanuel Author: Reinicke, Emanuel Recipient: Haeckel, Ernst Corporation: Wilhelm Engelmann Verlagsbuchhandlung Dating: 19.05.1900