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
BRIEF [O.A.] Beck, Alberto Author: Beck, Alberto Recipient: Haeckel, Ernst Corporation: Mineral de San Sebastian Dating: 11.05.1903
BRIEF [O.A.] Schleicher, Fréres Author: Schleicher, Fréres Recipient: Haeckel, Ernst Dating: 25.07.1903
