POSTKARTE Blochmann, Friedrich Author: Blochmann, Friedrich Recipient: Haeckel, Ernst Dating: 15.05.1903
BRIEF OHNE UMSCHLAG Becker, Daniel Georg Author: Becker, Daniel Georg Recipient: Haeckel, Ernst Dating: 06.10.1903
POSTKARTE Bockelmann, Friedrich Author: Bockelmann, Friedrich Recipient: Haeckel, Ernst Dating: 14.02.1903
BRIEF OHNE UMSCHLAG Bockelmann, Friedrich Author: Bockelmann, Friedrich Recipient: Haeckel, Ernst Dating: 26.05.1903
BRIEF OHNE UMSCHLAG Bockelmann, Friedrich Author: Bockelmann, Friedrich Recipient: Haeckel, Ernst Dating: 02.07.1903
BRIEF OHNE UMSCHLAG Bockelmann, Friedrich Author: Bockelmann, Friedrich Recipient: Haeckel, Ernst Dating: 08.07.1903
BRIEF [O.A.] Anton, Günther Kurt Author: Anton, Günther Kurt Recipient: Haeckel, Ernst Dating: 08.05.1903