BRIEF [O.A.] Georgy, Ernst August Author: Georgy, Ernst August Recipient: Haeckel, Ernst Dating: 09.10.1904
BRIEF [O.A.] Georgy, Ernst August Author: Georgy, Ernst August Recipient: Haeckel, Ernst Dating: 10.12.1904
BRIEF [O.A.] Georgy, Ernst August Author: Georgy, Ernst August Recipient: Haeckel, Ernst Dating: 21.12.1904
BRIEF [O.A.] Grungich, Ernst August [?] Author: Grungich, Ernst August [?] Recipient: Haeckel, Ernst Dating: 11.10.1904
BRIEF OHNE UMSCHLAG Krukenberg, Gustav Author: Krukenberg, Gustav Recipient: Haeckel, Ernst Dating: 07.02.1904