BRIEF [O.A.] Nippold, W... K... A... Author: Nippold, W... K... A... Recipient: Haeckel, Ernst Dating: 14.10.1903
BRIEF [O.A.] Nippold, W... K... A... Author: Nippold, W... K... A... Recipient: Haeckel, Ernst Dating: 23.10.1903
BRIEF [O.A.] Ritter, Paul von Author: Ritter, Paul von Recipient: Haeckel, Ernst Corporation: Bibliographisches Institut Dating: 01.06.1903
BRIEF [O.A.] Ritter, Paul von Author: Ritter, Paul von Recipient: Haeckel, Ernst Corporation: Bibliographisches Institut Dating: 17.10.1903
BRIEF [O.A.] Holdener, Frid... Author: Holdener, Frid... Recipient: Haeckel, Ernst Dating: 18.07.1903
BRIEF [O.A.] Mazzocconi, Rudolf Author: Mazzocconi, Rudolf Recipient: Haeckel, Ernst Dating: 28.07.1903