BILDPOSTKARTE Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 18.04.1908
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 10.07.1919
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 19.07.1897
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 28.04.1905
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 01.06.1905
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 06.06.1905
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 26.06.1905
POSTKARTE Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 28.04.1906
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 02.11.1908
BRIEF [O.A.] Hilbert, A. Author: Hilbert, A. Recipient: Haeckel, Ernst Corporation: Verlagsbuchhandlung Georg Reimer in Berlin Dating: 30.06.1909