BRIEF [O.A.] Bartels, Edmund von Author: Bartels, Edmund von Recipient: Haeckel, Ernst Dating: 11.05.1861
BRIEF [O.A.] Bartels, Edmund von Author: Bartels, Edmund von Recipient: Haeckel, Ernst Dating: 20.07.1861
BRIEF [O.A.] Bartels, Edmund von Author: Bartels, Edmund von Recipient: Haeckel, Ernst Dating: 06.09.1861