BRIEF [O.A.] Sederholm, J... J... Author: Sederholm, J... J... Recipient: Haeckel, Ernst Dating: 03.07.1897
BRIEF [O.A.] Sederholm, J... J... Author: Sederholm, J... J... Recipient: Haeckel, Ernst Dating: 31.01.1898
BRIEF [O.A.] Sederholm, J... J... Author: Sederholm, J... J... Recipient: Haeckel, Ernst Dating: 20.11.1905
BRIEF [O.A.] Heikel, Gunnar Author: Heikel, Gunnar Recipient: Haeckel, Ernst Corporation: Frökontrollanstalt, Agrikultur- och Handelskemiska Laboratorium Dating: 21.04.1913