POSTKARTE Tecklenburg, Arthur Author: Tecklenburg, Arthur Recipient: Haeckel, Ernst Dating: 14.03.1907
BRIEF [O.A.] Tecklenburg, Arthur Author: Tecklenburg, Arthur Recipient: Haeckel, Ernst Dating: 14.02.1904
BRIEF [O.A.] Tecklenburg, Arthur Author: Tecklenburg, Arthur Recipient: Haeckel, Ernst Dating: 13.03.1904
POSTKARTE Tecklenburg, Arthur Author: Tecklenburg, Arthur Recipient: Haeckel, Ernst Dating: 11.12.1908
POSTKARTE Tecklenburg, Arthur Author: Tecklenburg, Arthur Recipient: Haeckel, Ernst Dating: 15.02.1903