BRIEF [O.A.] Guldan, Georg Anton Author: Guldan, Georg Anton Recipient: Haeckel, Ernst Dating: 14.08.1876
BRIEF [O.A.] Ginn, Edwin Author: Ginn, Edwin Recipient: Haeckel, Ernst Corporation: Ginn & Company, Publishers of School and College Text-Books Dating: 08.10.1887
BRIEF OHNE UMSCHLAG Hall, G... Stanley Author: Hall, G... Stanley Recipient: Haeckel, Ernst Corporation: Clark University Dating: 15.03.1899
BRIEF OHNE UMSCHLAG Hall, G. Stanley Author: Hall, G. Stanley Recipient: Haeckel, Ernst Corporation: Clark University, President's Office Dating: 19.05.1899
BRIEF OHNE UMSCHLAG Burgess, Edward Author: Burgess, Edward Recipient: Haeckel, Ernst Dating: ??.09.1885
BRIEF [O.A.] Mark, Edward Laurens Author: Mark, Edward Laurens Recipient: Haeckel, Ernst Corporation: Harvard University – Zoological Laboratory Dating: 17.05.1881
BRIEF [O.A.] Mark, Edward Laurens Author: Mark, Edward Laurens Recipient: Haeckel, Ernst Corporation: Harvard University – Zoological Laboratory Dating: 26.10.1912
POSTKARTE Mark, Edward Laurens Author: Mark, Edward Laurens Recipient: Haeckel, Ernst Corporation: Harvard University - Museum of Comparative Zoology
POSTKARTE Mark, Edward Laurens Author: Mark, Edward Laurens Recipient: Haeckel, Ernst Dating: 08.06.1914
BRIEF [O.A.] Mark, Edward Laurens Author: Mark, Edward Laurens Recipient: Haeckel, Ernst Dating: 24.02.1891