Sørensen, H., M. Danø, O. Petersen, A. Povarennykh, A. Platonov, A. Tarashchan, and V. Belichenko. “On the Mineralogy and Paragenesis of Tugtupite Na8Al2Be2Si8O24(Cl,S)2 from the Ilímaussaq Alkaline Intrusion, South Greenland”. Bulletin Grønlands Geologiske Undersøgelse, vol. 95, June 1971, pp. 3-57, doi:10.34194/bullggu.v95.6635.