BRIEF [O.A.] Hoch, R... Author: Hoch, R... Recipient: Haeckel, Ernst Corporation: Freidenkerverein Wiesbaden Dating: 14.02.1904
BRIEF [O.A.] Wartensleben, J... C... Graf von Author: Wartensleben, J... C... Graf von Recipient: Haeckel, Ernst Dating: 26.09.1904
BRIEF [O.A.] Wartensleben, J... C... Graf von Author: Wartensleben, J... C... Graf von Recipient: Haeckel, Ernst Dating: 02.09.1904
TELEGRAMM Schleiden, Eleonore Author: Schleiden, Eleonore Recipient: Haeckel, Ernst Dating: 16.02.1904
BRIEF [O.A.] Rehbaum, Theobald Author: Rehbaum, Theobald Recipient: Haeckel, Ernst Dating: 15.02.1904