BRIEF [O.A.] Wagenschieber, W... Author: Wagenschieber, W... Recipient: Haeckel, Ernst Dating: 30.04.1870
BRIEF [O.A.] Wagenschieber, W... Author: Wagenschieber, W... Recipient: Haeckel, Ernst Dating: 24.05.1870
BRIEF [O.A.] Charisius, A... Author: Charisius, A... Recipient: Haeckel, Ernst Corporation: Lüderitz'sche Verlagsbuchhandlung Dating: 17.06.1870
BRIEF [O.A.] Ratzel, Friedrich Author: Ratzel, Friedrich Recipient: Haeckel, Ernst Dating: 08.02.1870
BRIEF [O.A.] Ratzel, Friedrich Author: Ratzel, Friedrich Recipient: Haeckel, Ernst Dating: 25.06.1870