BRIEF OHNE UMSCHLAG Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 15.08.1876
BRIEF [O.A.] Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 27.02.1881
BRIEF [O.A.] Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 04.06.1882
BRIEF [O.A.] Rottenburg, Paul von Author: Rottenburg, Paul von Recipient: Haeckel, Ernst Dating: 23.07.1882