BRIEF [O.A.] Lindhagen, D... G... Author: Lindhagen, D... G... Recipient: Haeckel, Ernst Corporation: Académie Royale des Sciences Dating: 06.01.1883
BRIEF [O.A.] Leche, Wilhelm Author: Leche, Wilhelm Recipient: Haeckel, Ernst Corporation: Zootomiska Institut Dating: 03.02.1911
BRIEF [O.A.] Nathorst, Alfred Gabriel Author: Nathorst, Alfred Gabriel Recipient: Haeckel, Ernst Corporation: Geologisches Institut Dating: ??.??.1881
