POSTKARTE Grazie, Marie Eugenie delle Author: Grazie, Marie Eugenie delle Recipient: Haeckel, Ernst Dating: 22.08.1903
BRIEF [O.A.] Davidoff, Michael von Author: Davidoff, Michael von Recipient: Haeckel, Ernst Corporation: Laboratoire Russe de Zoologie Dating: 20.10.1903
ANSICHTSKARTE Dodel-Port, Arnold Author: Dodel-Port, Arnold Recipient: Haeckel, Ernst Dating: 16.03.1903