BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Corporation: Geologisches u. Mineralogisches Institut Dating: 22.05.190?
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 30.12.1894
BILDPOSTKARTE Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 04.07.1894
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 20.09.1895
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 28.12.1895
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 11.02.1897
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 27.07.1897
BRIEF [O.A.] Walther, Johannes Author: Walther, Johannes Recipient: Haeckel, Ernst Dating: 20.09.1891
