1. Undersökning Af En Svart Tung Stenart Ifrån Ytterby Stenbrott I Roslagen;Gadolin,1794
2. Über Die Beziehungen Der Eigenschaften Zu Den Atomgewichten Der Elemente;Mendeleev;Z. Chem.,1869
3. History of Rare Earth Applications, Rare Earth Market Today;Greinacher,1981
4. A family of new cobalt-base permanent magnet materials;Strnat;J. Appl. Phys.,1967
5. Pr-Fe and Nd-Fe-based materials—a new class of high-performance permanent-magnets;Croat;J. Appl. Phys.,1984