BRIEF [O.A.] Recipient: Haeckel, Ernst Corporation: Apollowerk G.m.b.H., Kunstanstalt und Verlag Dating: 03.06.1913
BRIEF [O.A.] Recipient: Haeckel, Ernst Corporation: Apollowerk G.m.b.H., Kunstanstalt und Verlag Dating: 28.07.1913
BRIEF OHNE UMSCHLAG Bandmann, Otto Author: Bandmann, Otto Recipient: Haeckel, Ernst Dating: ??.08.1913
BRIEF [O.A.] Jolowicz, Leo Author: Jolowicz, Leo Recipient: Haeckel, Ernst Corporation: Akademische Verlagsgesellschaft m.b.H. Dating: 24.04.1913
