BRIEF [O.A.] Breitkopf Author: Breitkopf Recipient: Haeckel, Ernst Corporation: Breitkopf & Härtel Dating: 17.11.1898
BRIEF OHNE UMSCHLAG Aarland, Georg Author: Aarland, Georg Recipient: Haeckel, Ernst Dating: 17.01.1898
BRIEF [O.A.] Meyer Author: Meyer Recipient: Haeckel, Ernst Corporation: Bibliographisches Institut Dating: 28.05.1898
BRIEF [O.A.] Hirzel, Georg Author: Hirzel, Georg Recipient: Haeckel, Ernst Corporation: S. Hirzel, Verlagsbuchhandlung Dating: 21.11.1898
BRIEF [O.A.] Schoeler, Heinrich von Author: Schoeler, Heinrich von Recipient: Haeckel, Ernst Dating: 25.10.1898
BRIEF [O.A.] Schoeler, Heinrich von Author: Schoeler, Heinrich von Recipient: Haeckel, Ernst Dating: 21.10.1898
Leuckart, Amélie, geb. Henke Author: Leuckart, Amélie, geb. Henke Recipient: Haeckel, Ernst Dating: 06.02.1898