BRIEF [O.A.] Bulova, Josef Adolf Author: Bulova, Josef Adolf Recipient: Haeckel, Ernst Dating: 28.04.1900
BRIEF OHNE UMSCHLAG Kühnel-Engelsberg, Rudolf Author: Kühnel-Engelsberg, Rudolf Recipient: Haeckel, Ernst Dating: 09.04.1900
BRIEF [O.A.] Thon, Ph... C... Karl Author: Thon, Ph... C... Karl Recipient: Haeckel, Ernst Dating: 25.01.1900
BRIEF [O.A.] Stern, Maximilian L. Author: Stern, Maximilian L. Recipient: Haeckel, Ernst Dating: 09.03.1900
BRIEF OHNE UMSCHLAG Lendenfeld, Robert von Author: Lendenfeld, Robert von Recipient: Haeckel, Ernst Corporation: K. K. Zoologisches Institut der Deutschen Universität Dating: 17.03.1900
BRIEF [O.A.] Kühnel-Engelsberg, Rudolf Author: Kühnel-Engelsberg, Rudolf Recipient: Haeckel, Ernst Dating: 28.02.1900
BRIEF [O.A.] Kühnel-Engelsberg, Rudolf Author: Kühnel-Engelsberg, Rudolf Recipient: Haeckel, Ernst Dating: 13.03.1900