Soen, Oen Ing, and Hans Pauly. “A Sulphide Paragenesis With Pyrrhotite and Marcasite in the Siderite-Cryolite Ore of Ivigtut, South Greenland”. Meddelelser Om Grønland, vol. 175, no. 5, Feb. 1967, p. 67 pp., https://tidsskrift.dk/meddrgroenland/article/view/156544.