TELEGRAMM Drugievic, Ferdinand Author: Drugievic, Ferdinand Recipient: Haeckel, Ernst Dating: 15.02.1908
BRIEF [O.A.] Graff, Ludwig von Author: Graff, Ludwig von Recipient: Haeckel, Ernst Corporation: Zool.-Zoot. Institut der K. K. Carl-Franzens-Universität Dating: 21.08.1908