BRIEF [O.A.] Nagel, Adolph Author: Nagel, Adolph Recipient: Haeckel, Ernst Corporation: Musikalien-Verlag Dating: 07.04.1905
BRIEF [O.A.] Nagel, Adolph Author: Nagel, Adolph Recipient: Haeckel, Ernst Corporation: Musikalien-Verlag Dating: 11.04.1905
BRIEF [O.A.] Heinichen, Arnold Author: Heinichen, Arnold Recipient: Haeckel, Ernst Dating: 18.02.1904