1. The use of ionization potentials;Ahrens;Geochim. et Cosmochim. Acta,1952
2. Ore deposits of the Western States;Emmons,1933
3. Geochemische Migration der Elemente;Fersman;Abh. zur prakt Geol und Begwirt,1929
4. Minerals of the Khibina and Lovozero Tundras;Fersman,1937
5. Elemente und Minerale pegmatitischer Gesteine;Goldschmidt;Nachr. Gesell. Wiss. Gottingen Math. Physik Klasse,1930