POSTKARTE Bauer, Karl; Bauer, Klotilde Author: Bauer, Karl; Bauer, Klotilde Recipient: Haeckel, Ernst; Haeckel, Agnes Dating: 28.12.1909
BRIEF OHNE UMSCHLAG Bauer, Karl; Bauer Klotilde Author: Bauer, Karl; Bauer Klotilde Recipient: Haeckel, Ernst Dating: 15.02.1909
BRIEF OHNE UMSCHLAG Albrecht, Erwin Author: Albrecht, Erwin Recipient: Haeckel, Ernst Dating: 15.02.1909