BRIEFENTWURF Haeckel, Ernst Author: Haeckel, Ernst Recipient: Cartellieri, Georg Maximilian Alexander Dating: 27.07.1914
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Breitenbach, Wilhelm Dating: 29.04.1908
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Breitenbach, Wilhelm Dating: 21.08.1908