BRIEF OHNE UMSCHLAG Krähmer, Ferdinand Author: Krähmer, Ferdinand Recipient: Haeckel, Ernst Corporation: Bibliographisches Institut Dating: 14.12.1905
BRIEF [O.A.] Weidenmüller. Joh... Author: Weidenmüller. Joh... Recipient: Haeckel, Ernst Corporation: Leipziger Freie Studentenschaft Dating: 23.06.1905
BRIEF [O.A.] John, Elisabeth Author: John, Elisabeth Recipient: Haeckel, Ernst Corporation: Lagerei-Berufsgenossenschaft, Sektion IX Dating: 29.04.1905
BRIEF [O.A.] Prokosch, E... Author: Prokosch, E... Recipient: Haeckel, Ernst Corporation: The University of Chicago Dating: 15.04.1905
BRIEF [O.A.] Prokosch, E... Author: Prokosch, E... Recipient: Haeckel, Ernst Corporation: The University of Chicago Dating: 07.04.1905
BRIEF [O.A.] Quelle Author: Quelle Recipient: Haeckel, Ernst Corporation: B. G. Teubner Buchhandlung Dating: 19.07.1905