BRIEF [O.A.] Kalckreuth, G...fin Author: Kalckreuth, G...fin Recipient: Haeckel, Ernst Dating: 05.12.1882
BRIEF [O.A.] Hergt, Bernhard Author: Hergt, Bernhard Recipient: Haeckel, Ernst Corporation: Herbarium Haußknecht Dating: 20.06.1912
BRIEF [O.A.] Leiningen-Westerburg, K... E... Graf von Author: Leiningen-Westerburg, K... E... Graf von Recipient: Haeckel, Ernst Dating: 11.08.1881