BRIEF OHNE UMSCHLAG Lehmann-Hohenberg, Johannes Author: Lehmann-Hohenberg, Johannes Recipient: Haeckel, Ernst Dating: 30.06.1905
BRIEF [O.A.] Lehmann-Hohenberg, Johannes Author: Lehmann-Hohenberg, Johannes Recipient: Haeckel, Ernst Corporation: Schriftleitung "Volksanwalt" Dating: 07.01.1905
BRIEF [O.A.] Lehmann-Hohenberg, Johannes Author: Lehmann-Hohenberg, Johannes Recipient: Haeckel, Ernst Dating: 09.07.1905