BRIEF [O.A.] Habellock, Herbert Author: Habellock, Herbert Recipient: Haeckel, Ernst Dating: 16.02.1914
BRIEF [O.A.] Habellock, Herbert Author: Habellock, Herbert Recipient: Haeckel, Ernst Dating: 17.02.1915
BRIEF [O.A.] Habellock, Herbert Author: Habellock, Herbert Recipient: Haeckel, Ernst Dating: 17.02.1918
BRIEF [O.A.] Haberland, E... Author: Haberland, E... Recipient: Haeckel, Ernst Corporation: E. Haberland Leipzig Dating: 23.05.1914
BRIEF [O.A.] Haberlandt, Gottlieb Author: Haberlandt, Gottlieb Recipient: Haeckel, Ernst Dating: 23.04.1901
