Upton, Brian G. J. “The Geology of Tugtutôq and Neighbouring Islands, South Greenland. Part IV: The Nepheline Syenites of the Hviddal Composite Dyke”. Meddelelser Om Grønland, vol. 169, no. 3, Dec. 1964, pp. 49-80, https://tidsskrift.dk/meddrgroenland/article/view/160425.