BRIEF [O.A.] Cunningham, D. J. Author: Cunningham, D. J. Recipient: Haeckel, Ernst Dating: 27.08.1881
BRIEF [O.A.] Forster, Willliam Author: Forster, Willliam Recipient: Haeckel, Ernst Dating: 27.05.1878
BRIEF OHNE UMSCHLAG Geddes, Patrick Author: Geddes, Patrick Recipient: Haeckel, Ernst Corporation: Sociological Society Dating: 02.02.1905
BRIEF OHNE UMSCHLAG Pfeiffer, Jurgen Edward Author: Pfeiffer, Jurgen Edward Recipient: Haeckel, Ernst Dating: 27.10.1875