BRIEF OHNE UMSCHLAG Darling, Ernest Willing Author: Darling, Ernest Willing Recipient: Haeckel, Ernst Dating: 22.09.1913
POSTKARTE Darling, Ernest Willing Author: Darling, Ernest Willing Recipient: Haeckel, Ernst Dating: 28.07.1913
POSTKARTE Darling, Ernest Willing Author: Darling, Ernest Willing Recipient: Haeckel, Ernst Corporation: Nature Man Dating: 24.10.1913