1. C. E. Holley, Jr., E. J. Huber, Jr., and F. B. Baker,Progress in the Science and Technology of the Rare Earths(Pergamon, Oxford, 1968), Vol. 3, pp. 343–433.
2. THE RARE-EARTH METALS
3. J. W. Ward, P. D. Kleinschmidt, and D. E. Peterson,Handbook on the Physics and Chemistry of the Actinides(North-Holland, Amsterdam, 1986) Chap. 7, pp. 309–412.