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
BRIEF [O.A.] Leiningen-Westerburg, K. E. Graf von Author: Leiningen-Westerburg, K. E. Graf von Recipient: Haeckel, Ernst Dating: 07.05.1904