BILDPOSTKARTE Schuster, Adolf Niklaus Author: Schuster, Adolf Niklaus Recipient: Haeckel, Ernst Dating: 16.05.1909
BRIEF OHNE UMSCHLAG Quevedo, Francisco A. Lafone; Outes, Félix Faustino Author: Quevedo, Francisco A. Lafone; Outes, Félix Faustino Recipient: Haeckel, Ernst Corporation: Museo de La Plata Dating: 09.02.1909