BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 22.05.1885
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 09.06.1885
BRIEF [O.A.] Semon, Richard W... Author: Semon, Richard W... Recipient: Haeckel, Ernst Dating: 15.03.1886
BRIEF [O.A.] Semon, Richard W... Author: Semon, Richard W... Recipient: Haeckel, Ernst Dating: 29.08.1886
BRIEF [O.A.] Donvito, Eduardo Author: Donvito, Eduardo Recipient: Haeckel, Ernst Corporation: Il Pubblicista - La Gioventù Dating: 02.04.1912
BRIEF [O.A.] Eisig, Hugo Author: Eisig, Hugo Recipient: Haeckel, Ernst Corporation: Stazione Zoologica Napoli Dating: 12.05.1903