BRIEF [O.A.] Bols, Erven Lucas Author: Bols, Erven Lucas Recipient: Haeckel, Ernst Corporation: Amsterdamsche Likeurstokerij 'T Lootsje' Dating: 13.12.1907
BRIEF OHNE UMSCHLAG Scheffauer, Herman Author: Scheffauer, Herman Recipient: Haeckel, Ernst Dating: 09.05.1915
BRIEF [O.A.] Kreunen, H... M... Author: Kreunen, H... M... Recipient: Haeckel, Ernst Dating: 12.03.1907
BRIEF [O.A.] Kuyper, H... A... Author: Kuyper, H... A... Recipient: Haeckel, Ernst Dating: 01.08.1904
BRIEF [O.A.] Kerbert, Coenraad Author: Kerbert, Coenraad Recipient: Haeckel, Ernst Corporation: Koninklijk Zoologisch Genootschap Dating: 28.07.1894
BRIEF [O.A.] Kerbert, Coenraad Author: Kerbert, Coenraad Recipient: Haeckel, Ernst Corporation: Koninklijk Zoologisch Genootschap Dating: 13.12.1907