BRIEF [O.A.] Finsterlin, Hermann Author: Finsterlin, Hermann Recipient: Haeckel, Walter Dating: 13.02.1918
BRIEF [O.A.] Melliess, W... Author: Melliess, W... Recipient: Haeckel, Walter Corporation: Bibliographisches Institut Dating: 18.02.1921
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Walter Dating: 10.11.1919
BRIEF [O.A.] Haeckel, Heinrich Author: Haeckel, Heinrich Recipient: Haeckel, Walter Dating: 14.12.1919
BRIEF OHNE UMSCHLAG Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Walter Dating: ??.12.1914
BRIEF OHNE UMSCHLAG Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Walter Dating: 29.05.1912
POSTKARTE Wilckhaus, Charl... Author: Wilckhaus, Charl... Recipient: Haeckel, Walter Dating: 03.10.1911