BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 18.06.1890
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 01.09.1890
BRIEF OHNE UMSCHLAG Targioni Tozzetti, Author: Targioni Tozzetti, Recipient: Haeckel, Ernst Corporation: Gabinetto di Zoologia e Anatomia degli animali invertebrati Dating: 24.01.1890
BRIEF [O.A.] Haeckel, Ernst Author: Haeckel, Ernst Recipient: Krauseneck, Heinrich Dating: 04.11.1890
BRIEF OHNE UMSCHLAG Haeckel, Ernst Author: Haeckel, Ernst Recipient: Rottenburg, Paul von Dating: 04.08.1890