BRIEF [O.A.] Romberg, Heinrich Author: Romberg, Heinrich Recipient: Haeckel, Ernst Dating: 01.04.1866
BRIEF [O.A.] Romberg, Heinrich Author: Romberg, Heinrich Recipient: Haeckel, Ernst Dating: 01.02.1869
BRIEF [O.A.] Romberg, Heinrich Author: Romberg, Heinrich Recipient: Haeckel, Ernst Dating: 15.02.1891