BILDPOSTKARTE Schuster, Adolf Niklaus Author: Schuster, Adolf Niklaus Recipient: Haeckel, Ernst Dating: 14.04.1906
BILDPOSTKARTE Sokolowsky, Alexander Author: Sokolowsky, Alexander Recipient: Haeckel, Ernst Dating: 29.07.1907
BILDPOSTKARTE Crompton, Ella von Author: Crompton, Ella von Recipient: Haeckel, Ernst Dating: 30.08.1918
BILDPOSTKARTE Haeckel, Ernst Author: Haeckel, Ernst Recipient: Gruyter, Walter de Corporation: Zoologisches Institut der Universität Jena Dating: 01.01.1911