BRIEF [O.A.] Gmelin, Johann Georg Author: Gmelin, Johann Georg Recipient: Haeckel, Ernst Dating: 05.09.1909
BRIEF [O.A.] Georgii, Eberhard Author: Georgii, Eberhard Recipient: Haeckel, Ernst Dating: 15.02.1904
BRIEF [O.A.] Grün, Robb... S... Author: Grün, Robb... S... Recipient: Haeckel, Ernst Dating: 09.01.1893
BRIEF [O.A.] Haecker, Valentin Author: Haecker, Valentin Recipient: Haeckel, Ernst Dating: 06.07.1904
BRIEF [O.A.] Haecker, Valentin Author: Haecker, Valentin Recipient: Haeckel, Ernst Dating: 11.07.1904
BRIEF [O.A.] Kaltenbach, Hedwig Author: Kaltenbach, Hedwig Recipient: Haeckel, Ernst Dating: 17.03.1908
BRIEF [O.A.] Lampert, Kurt Author: Lampert, Kurt Recipient: Haeckel, Ernst Corporation: Königliches Naturalien-Cabinett Dating: 19.04.1893