BRIEF OHNE UMSCHLAG Michael, Alexander Author: Michael, Alexander Recipient: Haeckel, Ernst Dating: 11.06.1901
BRIEF OHNE UMSCHLAG Laishley, Richard Author: Laishley, Richard Recipient: Haeckel, Ernst Dating: 15.06.1887
BRIEF OHNE UMSCHLAG Thompson, Robert Author: Thompson, Robert Recipient: Haeckel, Ernst Corporation: Milner & Thompson Dating: 09.01.1901