BRIEF [O.A.] Schmertzing, Adolf Author: Schmertzing, Adolf Recipient: Haeckel, Ernst Dating: 21.01.1875
BRIEF [O.A.] Schmertzing, Adolf Author: Schmertzing, Adolf Recipient: Haeckel, Ernst Dating: 17.07.1875
BRIEF [O.A.] Schmertzing, Adolf Author: Schmertzing, Adolf Recipient: Haeckel, Ernst Dating: 17.08.1880
BRIEF [O.A.] Rozsnyay, Calman von Author: Rozsnyay, Calman von Recipient: Haeckel, Ernst Dating: 14.03.1917
BRIEF [O.A.] Rappard, Paula von Author: Rappard, Paula von Recipient: Haeckel, Ernst Dating: 25.04.1918
BRIEF [O.A.] Hertzka, Theodor Author: Hertzka, Theodor Recipient: Haeckel, Ernst Corporation: Redaction der "Pester Montagsblätter" Dating: 06.11.1871