1. F. H. Spedding, B. J. Beaudry, J. J., Croat and P. E. Palmer, Proc. Inter-Amer. Conf. Materials Technology, San Antonio (Texas), May (1968).
2. B. J. Beaudry, P. E. Palmer, Proc. 11th Rare Earth. Research Conf. Traverse City (Michigan), October (1974).
3. Progress in the Science and Technology of Rare Earths,1964
4. K. A. Gschneidner, Jr. and L. Eyring (Eds.), Handbook on the Physics and Chemistry of Rare Earths, North-Holland Publishing Co., Amsterdam.
5. H. F. Mark, J. J. McKeita, D. F. Othmer (Eds.) and Anthony Standen (Ex-Ed.), Encyclopaedia of Chemical Technology, Vol. 17, p. 143.