BRIEFENTWURF Sprenger, Therese Author: Sprenger, Therese Recipient: Haeckel, Ernst Dating: 23.12.1912
BRIEFENTWURF Cartellieri, Georg Maximilian Alexander Author: Cartellieri, Georg Maximilian Alexander Recipient: Haeckel, Ernst Dating: 06.07.1914
BRIEFENTWURF Michels, Victor Karl Theodor Author: Michels, Victor Karl Theodor Recipient: Haeckel, Ernst Corporation: Senat der Universität Jena Dating: 02.12.1916
BRIEFENTWURF Hedemann, Justus Wilhelm Author: Hedemann, Justus Wilhelm Recipient: Haeckel, Ernst Dating: 06.06.1919
BRIEFENTWURF Haeckel, Ernst Author: Haeckel, Ernst Recipient: Cartellieri, Georg Maximilian Alexander Dating: 27.07.1914