BRIEF OHNE UMSCHLAG Benninghoven Author: Benninghoven Recipient: Haeckel, Ernst Corporation: Dr. med. Benninghoven & Messing Dating: 25.02.1894
BRIEF OHNE UMSCHLAG Bertheau, Georg Author: Bertheau, Georg Recipient: Haeckel, Ernst Dating: 15.02.1894
POSTKARTE Recipient: Haeckel, Ernst Corporation: August Blumenthal, Transitus – Hamburg Dating: 09.12.1894
POSTKARTE Hartlaub, Clemens Author: Hartlaub, Clemens Recipient: Haeckel, Ernst Corporation: Die Königl. Biologische Anstalt Dating: 21.03.1894
BRIEF OHNE UMSCHLAG Anton, Günther Kurt Author: Anton, Günther Kurt Recipient: Haeckel, Ernst Dating: 07.03.1894
BRIEF OHNE UMSCHLAG Bölsche, Wilhelm Author: Bölsche, Wilhelm Recipient: Haeckel, Ernst Dating: 04.11.1894
